P204F00 fault, VW has no fix!

ghohouston · Feb 27, 2022

These dealers should really educate on d.e.f. systems because honestly they're not THAT hard to troubleshoot.

You have a d.e.f. pump that feeds a d.e.f. injector. Said injector has a solenoid so it's obviouslyelectronically controlled. It sprays d.e.f. into your s.c.r. to reduce n.o.x. emissions. P204f is a generic code, stating you have a problem within your dosing controller, and generally you can find other faults, which caused the code. N.o.x. sensors obviously read the parts per million present of nitrous oxide in your exhaust, and this is used to calculate when and how much d.e.f. is injected.

MrCypherr · Feb 27, 2022

The dealer has testplans on their scan tools that run tests for all the components. So its not that hard to diag whats wrong. Now some codes like, NOx SCR below efficiency could also be a bad NOx sensor even though it hasnt thrown a code. Regardless, the P204F code has been confirmed by VW that there is no fix for it after the "diesel gate software fix" software fix update.

watatrp · Feb 27, 2022

So it sounds like VW knows they have a problem that is not able to be solved. The diesel gate software fix caused a whole new set of problems and they want to just look the other way hoping that attrition, deletes and third party software updates will reduce the problems down to a point where they can just ignore it. What a wonderful way to run a business.

eugene89us · Feb 28, 2022

Without a doubt I think it is the right business decision from a standpoint that TDI community has gone from mainstream to a niche community of those of us that enjoy our diesels. I am not saying this is morally right - it certainly is not - but I can see how additional modifications to the tune can result in requirement for additional EPA involvement and approvals. And with expense and government red tape, they are just looking elsewhere.

Hence the reason I suggested Kerma tune. It keeps the car legal in ways that maintain all emissions components, car continues to undergo regens via DPF (although at reduced frequency due to reduced sooting - I understand there is a minor improvement in engine efficiency), and SCr continues to be operational. On BMW N47 (as opposed to VW), the SCr system actually consumes more adblue, because lower sooting performance results in increase in NOx in those engines. To counteract, system doubles the use of AdBlue and at the tailpipe still maintains stringent requirements to pass the sniffer test in those states. I am not in a sniffer state - we don't even have annual inspection anymore - but I am still environment-conscious. So in my opinion, having the tune tune that improved many things while also maintaining environment friendliness is a definitive win for me. Plus, it reduces aggressive nature of our cars and reduces coolant from cooking prematurely (which causes clogging of heater cores and oil coolers --- see my other threads on that). In the grand scheme of things, what is a few hundred dollars taking into account the thousands we got for our restitution. That is how I explained that to myself and I do not regret that decision one bit since I have had Kerma tuning done.

EDIT: Of note, don't think that I am a spokesperson for Kerma or that I know anything other than my personal experiences with it and my discussion with the Kerma team. I paid full price for both engine and DSG tunes, although I got it around the holidays and Kerma was running a promotion on their site. I have nothing but good things to say about them, their sales team is awesome and their engineer is a brilliant individual as well as a Veteran. I will support them any day, they gave my TDI a second chance at being enjoyable (even more enjoyable than my BMW in some ways. LOL)

x1800MODMY360x · Feb 28, 2022

eugene89us said:
Without a doubt I think it is the right business decision from a standpoint that TDI community has gone from mainstream to a niche community of those of us that enjoy our diesels. I am not saying this is morally right - it certainly is not - but I can see how additional modifications to the tune can result in requirement for additional EPA involvement and approvals. And with expense and government red tape, they are just looking elsewhere.

Hence the reason I suggested Kerma tune. It keeps the car legal in ways that maintain all emissions components, car continues to undergo regens via DPF (although at reduced frequency due to reduced sooting - I understand there is a minor improvement in engine efficiency), and SCr continues to be operational. On BMW N47 (as opposed to VW), the SCr system actually consumes more adblue, because lower sooting performance results in increase in NOx in those engines. To counteract, system doubles the use of AdBlue and at the tailpipe still maintains stringent requirements to pass the sniffer test in those states. I am not in a sniffer state - we don't even have annual inspection anymore - but I am still environment-conscious. So in my opinion, having the tune tune that improved many things while also maintaining environment friendliness is a definitive win for me. Plus, it reduces aggressive nature of our cars and reduces coolant from cooking prematurely (which causes clogging of heater cores and oil coolers --- see my other threads on that). In the grand scheme of things, what is a few hundred dollars taking into account the thousands we got for our restitution. That is how I explained that to myself and I do not regret that decision one bit since I have had Kerma tuning done.

EDIT: Of note, don't think that I am a spokesperson for Kerma or that I know anything other than my personal experiences with it and my discussion with the Kerma team. I paid full price for both engine and DSG tunes, although I got it around the holidays and Kerma was running a promotion on their site. I have nothing but good things to say about them, their sales team is awesome and their engineer is a brilliant individual as well as a Veteran. I will support them any day, they gave my TDI a second chance at being enjoyable (even more enjoyable than my BMW in some ways. LOL)

Malone also does tunes with the emissions system intact btw.

I do agree that I rather have the egr produce less soot and use more adblue. Makes the engine run better in the long run.

eugene89us · Feb 28, 2022

@x1800MODMY360x I do not know this personally and I cannot personally confirm the statements that follow, but I have some friends that are in such business. Someone mentioned that the approach Malone takes (at least specifically to BMWs) is to shut off components and shut off the possible MIL debounce from this. So instead of adjusting maps and teaching car to work with new maps, it actually just turns off ability to throw MIL when car operates outside factory maps. Some components you have to approach that way as there is no way around that, but others can be meticulously adjusted to still be able to communicate and report errors with that module. Simply adjusting maps and turning off MIL errors when car notices difference may not be the best approach. Kerma guys take meticulous approach for most things. Hence you may have different way components work, but if you were to unplug those adjusted components, you will get MIL on Kerma and nothing on Malone. But once again, I never independently confirmed that, I am just regurgitating what I know. I can tell you if I unplug EGR module or AdBlue module, the car illuminates MIL. Although their functioning changes with adjustment to tune itself. After all, I want my car to work with improved tuning, but I also want it to tell me if those components suddenly malfunction. Some cars are tuned in such a way that you will have to get to an engine fire and it still won't throw MIL warning. This may the an extreme example, but that is the best way I know to explain this.

tikal · Feb 28, 2022

lowlife said:
Delete caused heater core.

Could you please elaborate on the above?

x1800MODMY360x · Feb 28, 2022

tikal said:
Could you please elaborate on the above?

The NMS 2012+ Passats TDI heater core clogs when the G13 Coolant heats up during regen with the bad heater core.

Deleting the emissions system prevents the heater core from clogging again. Or use G12 which I never had a heater core issue yet.

tikal · Feb 28, 2022

^^ Thanks. The sentence I quoted was not clear to me. I appreciate the clarification. Delete = less likelihood of heater core clogging.

lowlife · Feb 28, 2022

tikal said:
Could you please elaborate on the above?

That would be the fingers typing ahead of the brain. Delete would hopefully prevent another heater core etc. First post edited

tikal · Mar 1, 2022

lowlife said:
That would be the fingers typing ahead of the brain. Delete would hopefully prevent another heater core etc. First post edited

Excellent and thank you.

ghohouston · Mar 20, 2022

MrCypherr said:
The dealer has testplans on their scan tools that run tests for all the components. So its not that hard to diag whats wrong. Now some codes like, NOx SCR below efficiency could also be a bad NOx sensor even though it hasnt thrown a code. Regardless, the P204F code has been confirmed by VW that there is no fix for it after the "diesel gate software fix" software fix update.

That's ridiculous. I work on Tier 4 interim and Tier 4 final engines almost daily on heavy equipment. P204f code is a generic code that means there is a further issue in the aftertreatement system.

watatrp · Mar 21, 2022

ghohouston said:
That's ridiculous. I work on Tier 4 interim and Tier 4 final engines almost daily on heavy equipment. P204f code is a generic code that means there is a further issue in the aftertreatement system.

I'm still amazed that VW knows about this problem and doesn't want to fix it. I can spend hundreds of dollars to fix it on my own but VW turns a blind eye.

beezy2015 · Mar 31, 2022

I had planned on buying a KermaTDI, but have been putting it off. This past weekend I got the P204F code with 200 miles till 0 DEF fluid. Well i went past that as i was on a 3 hour trip and was about 9pm that night. risking it till i got into town. Kept saying no restart if i shut off the engine. As soon as I got to my destination I turned off the car and it started back up and the DEF fluid icon went away. So my question is, if I get the KermaTDI now, will that take care of this issue? I don't wanna mess with the dealership its my day to day driver. I've read a lot of the same issues and no VW fix, just looking for the most reliable fix for now. Thanks!

DCoartney · Apr 4, 2022

Our saga continues:

Normal countdown commenced
Refilled AdBlue prior to leaving on 3-hour trip. System seemed to reset.
Warning returned starting at 100 miles to "no start" and continued to count down.
Tried resetting again, cleared P204F, but amber AdBlue and amber wrench light stayed on and continued to count down.
Arrived at dealership with 10 miles to no start.
VW case manager called with update. He is working with dealership. Says regional tech rep (can't remember proper title) will determine from data whether coming on site is warranted. Possibility of "no fix" status.

Like beezy2015, I'm interested to know if Kerma or Malone will make the car reliable and not put our daughter in danger by being stranded at night at a fuel stop or rest area -- and still pass Milwaukee emissions test.

watatrp · Apr 5, 2022

DCoartney said:
Our saga continues:

Normal countdown commenced

Refilled AdBlue prior to leaving on 3-hour trip. System seemed to reset.

Warning returned starting at 100 miles to "no start" and continued to count down.

Tried resetting again, cleared P204F, but amber AdBlue and amber wrench light stayed on and continued to count down.

Arrived at dealership with 10 miles to no start.

VW case manager called with update. He is working with dealership. Says regional tech rep (can't remember proper title) will determine from data whether coming on site is warranted. Possibility of "no fix" status.

Like beezy2015, I'm interested to know if Kerma or Malone will make the car reliable and not put our daughter in danger by being stranded at night at a fuel stop or rest area -- and still pass Milwaukee emissions test.

According to Kerma, it does fix these problems. Just waiting for my schedule to free up so I can get some time to do this. In the mean time, I just put up with the alerts. Long trips at higher speeds in cold temps always causes this for me. My local dealership has already replaced a few parts on mine two years ago but the software glitch is still there. Be nice if VW would help out with the real fix that a tune would provide. I'm sure the repairs VW has done already to my car far outweigh the cost of a tune.

eugene89us · Apr 5, 2022

Curiously enough, the only time I had AdBlue trouble was when the DEF heater went out around 30k on ODO back in 2015 or 2016. Since that was replaced under new car warranty, have not had problems yet before VW official "fix" and after the "fix". AdBlue use never really appreciably increased as far as I can tell. Nevertheless, car became uncomfortable to drive. Having had original dieselgate tune for 3 to 4 years allowed me to get used to it, and the new factory tune just felt poorly timed. Gear shifts appeared too delayed, every morning I had a voice in my head say "shift up already" and accelerating on highway was the opposite - car would be sluggish but refuses to downshift. So my decision for Kerma tune was not due to a problem, it was primarily due to lack of enjoyment in my car. At that point, I already bought BMW diesel 3-series and had it tuned by Kerma as well. Having experienced being able to break traction with my tires if I wanted to sealed my decision. Since TDI is still in the family, I bought both tunes.

I would still recommend stopping with these delays and get it tuned. As a matter of fact, reach out to Kerma and discuss possibility of a "trial run". These guys stand behind their product. I was unsure if I wanted the DSG tune, I think I spoke to Jason, who said "Try it out. If you hate it, we will revert the car back to stock and refund you." Well guess what, did not need to do that, having that tune done and I was in heaven. At a bare minimum, give up $600 for engine tune and hold off at least for now on DSG tune if money is a concern. Engine tune is not as complex as DSG tune, the longest part is it will take a week to get the QPro unit shipped to you. It is as simple as plug it in - read off the file, send the file to the Kerma guys, and within hours you will get a new file to load up. Tuning will take 15 minutes tops. The time countdown on QPro I think started showing 45 minutes, but after each step is done, the time was dropping in 10 minute increments rapidly. I think 15 minutes maybe 20 minutes, but no more. There is no excuse waiting on "having more time", I did it while working 2 jobs. All it took is for me to get home, plug it in, send the file and go to bed. Next day, downloaded tune file, loaded on Qpro, connected to car, and read some news while the progress bar went on its way. 15 minutes later and I was cruising along testing out the tune.

740GLE · Apr 6, 2022

beezy2015 said:
I had planned on buying a KermaTDI, but have been putting it off. This past weekend I got the P204F code with 200 miles till 0 DEF fluid. Well i went past that as i was on a 3 hour trip and was about 9pm that night. risking it till i got into town. Kept saying no restart if i shut off the engine. As soon as I got to my destination I turned off the car and it started back up and the DEF fluid icon went away. So my question is, if I get the KermaTDI now, will that take care of this issue? I don't wanna mess with the dealership its my day to day driver. I've read a lot of the same issues and no VW fix, just looking for the most reliable fix for now. Thanks!

why go with Kerma when you can go with malone and then be future proof for possible EGR/EDF/SCR deletes?

eugene89us · Apr 6, 2022

@740GLE There are a few concerns with that. I was in a position (before I decided on Kerma for both of my diesels) to code out EGR and SCR, while leaving DPF in place. The car stunk to high Heavens, especially in cold weather. I always felt NOx were odorless, but whatever it was, once weather turned cooler, the exhaust left a very sour smell to the garage. I went back stock, smell disappeared. Of course, I feel BMW has more reliable SCR system compared to VW, since it has been trouble free for 80K miles since I bought the car in Dec 2017. I have had a few issues with TDI's SCR module, unfortunately, as mentioned above. From discussion with DPF deleted individuals, you also get some smoke. So now, you have a stinky smoking car. Will it be more trouble-free? I think probably so, but I decided having family and a child, I would rather deal with issues than expose all of us to those irritants. And believe me, I am not an environmentalist, I just could not stand the smell myself, it was nasty and it got worse over time.

Second thing to consider - EGR delete. You do not want to delete EGR completely. I agree, it is a stupid design that dirties the engine on purpose, I clean my intake annually as part of my regular maintenance with LiquiMoly Diesel Intake Cleaner. VW has a more complex EGR than my BMW. BMW has an EGR valve then EGR cooler going straight from exhaust manifold back into the plastic intake. VW has both high pressure and low pressure EGRs (fancy!). Anyways, our diesels are very efficient in terms of reduced loss of energy to heat. When my EGR was off temporarily, engine took 3 times longer to warm up in winter. I would often take a 30 mile drive and the engine oil temp needle would just be halfway to the warmed up side! You want *adaptive* EGR. You want it to help heat up the engine/coolant/oil quickly especially in cold months, and then shut off when the car is warm. This will reduce unnecessary wear from engine running cold for too long. Yes, you certainly accept carbon deposits in intake but it is a small price to pay, especially if your EGR is open only for a warm up portion of your drive. It certainly does have its benefits. BMW with its non-US B47 engine actually re-did the EGR system to start from AFTER the DPF. That way, you would recirculate filtered exhaust instead of dirty exhaust, but unfortunately that engine never made in to USA. That is one thing I wish I had. Either case, EGR reduces combustion temperatures and thus reduces NOx. With adaptive EGR, you would increase NOx production however active SCr will adjust to take care of that. And at the end, you will still remain within VW's agreed upon limits on NOx.

So the decision is yours at the end. Kerma keeps your emissions intact but adjusts a lot of the parameters to improve their reliability. You still keep a road-legal vehicle while enjoying the benefits of a tuned car. I feel Kerma is a version of BMW's MPPSK - a road legal tuning package you can install on a vehicle. I am not in an emission state, we don't even have annual inspection anymore, but I decided my family's health is not worth the risk of jeopardy. And in the future if DPF clogs up, EGR fails, or SCR croaks, I may sing a different tune. For now, all is peachy and I am knocking on wood just to be safe. LOL.

x1800MODMY360x · Apr 6, 2022

eugene89us said:
@740GLE There are a few concerns with that. I was in a position (before I decided on Kerma for both of my diesels) to code out EGR and SCR, while leaving DPF in place. The car stunk to high Heavens, especially in cold weather. I always felt NOx were odorless, but whatever it was, once weather turned cooler, the exhaust left a very sour smell to the garage. I went back stock, smell disappeared. Of course, I feel BMW has more reliable SCR system compared to VW, since it has been trouble free for 80K miles since I bought the car in Dec 2017. I have had a few issues with TDI's SCR module, unfortunately, as mentioned above. From discussion with DPF deleted individuals, you also get some smoke. So now, you have a stinky smoking car. Will it be more trouble-free? I think probably so, but I decided having family and a child, I would rather deal with issues than expose all of us to those irritants. And believe me, I am not an environmentalist, I just could not stand the smell myself, it was nasty and it got worse over time.

Second thing to consider - EGR delete. You do not want to delete EGR completely. I agree, it is a stupid design that dirties the engine on purpose, I clean my intake annually as part of my regular maintenance with LiquiMoly Diesel Intake Cleaner. VW has a more complex EGR than my BMW. BMW has an EGR valve then EGR cooler going straight from exhaust manifold back into the plastic intake. VW has both high pressure and low pressure EGRs (fancy!). Anyways, our diesels are very efficient in terms of reduced loss of energy to heat. When my EGR was off temporarily, engine took 3 times longer to warm up in winter. I would often take a 30 mile drive and the engine oil temp needle would just be halfway to the warmed up side! You want *adaptive* EGR. You want it to help heat up the engine/coolant/oil quickly especially in cold months, and then shut off when the car is warm. This will reduce unnecessary wear from engine running cold for too long. Yes, you certainly accept carbon deposits in intake but it is a small price to pay, especially if your EGR is open only for a warm up portion of your drive. It certainly does have its benefits. BMW with its non-US B47 engine actually re-did the EGR system to start from AFTER the DPF. That way, you would recirculate filtered exhaust instead of dirty exhaust, but unfortunately that engine never made in to USA. That is one thing I wish I had. Either case, EGR reduces combustion temperatures and thus reduces NOx. With adaptive EGR, you would increase NOx production however active SCr will adjust to take care of that. And at the end, you will still remain within VW's agreed upon limits on NOx.

So the decision is yours at the end. Kerma keeps your emissions intact but adjusts a lot of the parameters to improve their reliability. You still keep a road-legal vehicle while enjoying the benefits of a tuned car. I feel Kerma is a version of BMW's MPPSK - a road legal tuning package you can install on a vehicle. I am not in an emission state, we don't even have annual inspection anymore, but I decided my family's health is not worth the risk of jeopardy. And in the future if DPF clogs up, EGR fails, or SCR croaks, I may sing a different tune. For now, all is peachy and I am knocking on wood just to be safe. LOL.

Malone also offer the "Dynamic EGR" which I believe VW did before the dieselgate fix. I live in a hot state and currently running the EGR delete (Which is still there but tuned so no error if unplugged), which during winter it took an extra 2-4mins to warm up the car. But since the EGR is closed my regen went from average 315 miles to 562 miles between regen, MPG increased from 38 to 42MPG, also engine temp drop 2-6 degrees.

The only downside is DEF usage has increased to offset NOx with the EGR closed but still compliant with emissions testing.

740GLE · Apr 8, 2022

eugene89us said:
@740GLE There are a few concerns with that. I was in a position (before I decided on Kerma for both of my diesels) to code out EGR and SCR, while leaving DPF in place. The car stunk to high Heavens, especially in cold weather. I always felt NOx were odorless, but whatever it was, once weather turned cooler, the exhaust left a very sour smell to the garage..

The stink you probably noted was from EGR not being functional vs NOx, if you just turned off the SCR and left EGR on id wager it'd be stink free. Just a thought.

Agreed that EGR is needed for colder climates.

eugene89us · Apr 8, 2022

@740GLE Haha. I can neither confirm nor deny that I have dynamic EGR on all my German diesels. I also cannot confirm nor deny that my oil appears less sooty when I change it compared to cars I serviced that did not have dynamic EGR. Tuning cars is evil and you all are going to hell (including me, maybe, since I cannot confirm nor deny that). LOL.

The interesting thing, though, is that the BMW actually started to gulp Ad Blue when I played with EGR (used to go 10K without refill DEF light, and with EGR mods, it needs refills every 6k miles) whereas TDI though may have increased DEF usage, I have yet to get a notification on refilling AdBlue. It is using it, I know, because the level is dropping (from overfilled to "I cannot see it anymore through the hole") but for some reason TDI uses less than BWM. May have something to do with the programming or sensors. After all, BMW cheated much less than VW did. I love all my diesels equally, though. There is no other car that can compare to our Passat with the legroom and trunk space. I can barely fit all my luggage into F30 BMW when going to the airport. So I love them both.

Nevertheless, I strongly recommend dynamic EGR (even in warmer climates, since we still get cold spells here for months) and keeping SCR on as long as it is not causing a problem, since shutting EGR will increase NOX emissions and SCR can help to reduce them. Although I feel climate catastrophists overblow it sometimes, I still love our environment and we need to remain diligent with it. Once SCR starts to crap out, then do what makes financial sense. I also believe in DPF. These are rated, I believe for over 200k km and can last even beyond that. My F30 has calculated soot mass of only 27 grams with almost 80,000 miles. TDI I think has not much more with 110k miles. They don't cause as much trouble. I also feel the regens have decreased in frequency. My F30 average is 647km between regens. But once again, I say this now, but once DPF clogs and SCR craps out and I get a $10,000 bill, I may consider going "nuclear" option and rolling coal. Praying won't have to be in that predicament.

I am a believer in Kerma because I used Kerma and it transformed the car. I hope it makes it last longer too, since tune was less for excited driving and more for making driving simply enjoyable. @x1800MODMY360x Malone has a strong presence on the market and I am sure they make great tunes also. I just cannot comment from experience since I never tuned with them.

x1800MODMY360x · Apr 8, 2022

eugene89us said:
@740GLE I am a believer in Kerma because I used Kerma and it transformed the car. I hope it makes it last longer too, since tune was less for excited driving and more for making driving simply enjoyable. @x1800MODMY360x Malone has a strong presence on the market and I am sure they make great tunes also. I just cannot comment from experience since I never tuned with them.

I mean, it's all about preference. I didn't know Malone does EGR delete / Dynamic EGR. I mean EGR causes so many issues with systems. Also still emissions complianced even with EGR delete with the DPF/SCR in place.

GZ_22 · Apr 10, 2022

Soooo, basically I shouldn't go to the dealership cause they don't know what tf is going on... and I should get a tune for my car?

I was on a trip about 150 miles away and as I was getting closer the light came on to fill up otherwise the car won't start after 200 miles as well as the check engine light turned on and I checked the code and the P204F code came up. The next day I went and bought some DEF to put in the tank to fill it up. I filled it up and I didn't turn the car on cause I figured that it would have solved the problem. Also, I don't know much about vehicles and I do a lot of research before I ever bring my car in so that I know semi of what is going on and I won't be getting ripped off by dealerships because that is what they do. Anyways, after a couple hours of filling it up I go to turn the car on and both lights are still on. So, I drive it around for about 20 miles and nothing happens and neither light turns off. So, I clear the code for the engine light and hope that does something and it doesn't. So now I just have the countdown to death, as a comment mentioned earlier, and I am stuck on what to do. I had actually recently, about two weeks ago, got my NOx sensor replaced as well. I also use my car everyday and if I am not able to get my vehicle to turn on, I am kind of screwed. So I can take it to my mechanic and see what they have to say about it or I can take it to the dealership and have them keep my car and put me in a rental. If anyone knows anything about this please let me know. Thank you in advance.

Lightflyer1 · Apr 10, 2022

Just like anything else some dealerships are better than others. Same with independents. One of the trusted mechanics on the list is always preferable in a non warranty situation and sometimes with. First is to determine if you have any warranty that applies.

VW Emissions Modification Lookup

www.vwdieselinfo.com

If so then find the document that shows what is covered for your car. Get them to fix it under warranty. Learn the warranty terms if you plan to use it. You can't have a conversation if you don't know these details. If not under warranty I would find a trusted mechanic closer to you.

watatrp · Apr 11, 2022

GZ_22 said:
Soooo, basically I shouldn't go to the dealership cause they don't know what tf is going on... and I should get a tune for my car?

I was on a trip about 150 miles away and as I was getting closer the light came on to fill up otherwise the car won't start after 200 miles as well as the check engine light turned on and I checked the code and the P204F code came up. The next day I went and bought some DEF to put in the tank to fill it up. I filled it up and I didn't turn the car on cause I figured that it would have solved the problem. Also, I don't know much about vehicles and I do a lot of research before I ever bring my car in so that I know semi of what is going on and I won't be getting ripped off by dealerships because that is what they do. Anyways, after a couple hours of filling it up I go to turn the car on and both lights are still on. So, I drive it around for about 20 miles and nothing happens and neither light turns off. So, I clear the code for the engine light and hope that does something and it doesn't. So now I just have the countdown to death, as a comment mentioned earlier, and I am stuck on what to do. I had actually recently, about two weeks ago, got my NOx sensor replaced as well. I also use my car everyday and if I am not able to get my vehicle to turn on, I am kind of screwed. So I can take it to my mechanic and see what they have to say about it or I can take it to the dealership and have them keep my car and put me in a rental. If anyone knows anything about this please let me know. Thank you in advance.

My experience is that it never gets to the "no start" stage. I've gone down as low as 25 miles and then it disappeared but the cel stayed on. I've had it to the dealership for this. They kept it for 3 weeks and replaced a lot of parts. It didn't act up for almost a year but now it's back to the same old stuff. Now that's it's a little warmer, it doesn't do it. My theory is that driving at higher speeds for extended periods of time when the temps are below 35-40 degrees is what causes it. The sensor must think that it is using def fluid at a higher rate than it actually is and thinks that the tank is almost empty. It's a software glitch that hasn't been fixed yet. My plan is to do the Kerma "fix" as well as the DSG tune. I only have 65k on my car and the $1000 invested by me for the tunes seems to be worth it to make the car reliable. I still feel like VW should fix this or pay for the fix. I still have some warranty left but the time I have to invest to get this "fixed" by VW takes a lot of my time and I know that it is not a permanent fix now. Very frustrating indeed.

x1800MODMY360x · Apr 11, 2022

watatrp said:
Now that's it's a little warmer, it doesn't do it. My theory is that driving at higher speeds for extended periods of time when the temps are below 35-40 degrees is what causes it. The sensor must think that it is using def fluid at a higher rate than it actually is and thinks that the tank is almost empty. It's a software glitch that hasn't been fixed yet.

There was a TSB for the CKRA if the car was going 85mph for longer than 15mins it would throw a low DEF fluid countdown. I'm sure it was recalled and program before the dieselgate fix was out.

watatrp · Apr 11, 2022

x1800MODMY360x said:
There was a TSB for the CKRA if the car was going 85mph for longer than 15mins it would throw a low DEF fluid countdown. I'm sure it was recalled and program before the dieselgate fix was out.

I have an NMS version. I'm in the engineering field so I come to conclusions based on facts available. I know every time I go on an 80+ mile trip and temps are below 40 it will throw the code. Last week it was 42 degrees and no code. My speeds never get above 80 mph but usually around 75 mph. Mine has had the fix so that TSB issue should be taken care of. Plus the dealer replaced most components of the system and reprogrammed.

oilhammer · Apr 11, 2022

Yep, it is sadly a common problem, and I am still not sure they figured out a software fix for it. High speed, long distances, cold weather, that's what does it.

GZ_22 · Apr 13, 2022

GZ_22 said:
Soooo, basically I shouldn't go to the dealership cause they don't know what tf is going on... and I should get a tune for my car?

I was on a trip about 150 miles away and as I was getting closer the light came on to fill up otherwise the car won't start after 200 miles as well as the check engine light turned on and I checked the code and the P204F code came up. The next day I went and bought some DEF to put in the tank to fill it up. I filled it up and I didn't turn the car on cause I figured that it would have solved the problem. Also, I don't know much about vehicles and I do a lot of research before I ever bring my car in so that I know semi of what is going on and I won't be getting ripped off by dealerships because that is what they do. Anyways, after a couple hours of filling it up I go to turn the car on and both lights are still on. So, I drive it around for about 20 miles and nothing happens and neither light turns off. So, I clear the code for the engine light and hope that does something and it doesn't. So now I just have the countdown to death, as a comment mentioned earlier, and I am stuck on what to do. I had actually recently, about two weeks ago, got my NOx sensor replaced as well. I also use my car everyday and if I am not able to get my vehicle to turn on, I am kind of screwed. So I can take it to my mechanic and see what they have to say about it or I can take it to the dealership and have them keep my car and put me in a rental. If anyone knows anything about this please let me know. Thank you in advance.

UPDATE: I was driving back and after about 50 miles it did turn off. So I must have overfilled it and had to drive it around for a bit in order for it to sense that.

P204F00 fault, VW has no fix!

Veteran Member

Veteran Member

Veteran Member

Veteran Member

Veteran Member

Veteran Member

Veteran Member

Veteran Member

Veteran Member

Active member

Veteran Member

Veteran Member

Veteran Member

New member

Active member

Veteran Member

Veteran Member

Top Post Dawg

Veteran Member

Veteran Member

Top Post Dawg

Veteran Member

Veteran Member

New member

Top Post Dawg

Veteran Member

Veteran Member

Veteran Member

Certified Volkswagen Nut & Vendor

New member