MIL light on 2012 Passat 2012

My wife just drove from Maine to Georgia. (1100 miles) after arriving the car sat for a day... Maybe a small 10 mile trip to town. The. She got in to head to Atlanta, 60 miles away. When she started the car the engine malfunction light came on and has remained on since then. Since coming on it has been driven at freeway speeds 60 miles or more and also some in city driving. The fuel tank has about 300 miles on it... Here are some details with the car:
2012 passat tdi sel
68000 miles
Oil changed, fuel filter about 2k ago

I am trying to figure out what is causing this. What is the best way to do this? Any thoughts on what causes it to come on?


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sorry...not enough information. W/o a scan, there's no way to know what's going on.
Dealership? A club member with VCDS?
Personally, I wouldn't make the return trip w/o finding out what the problem is.

The MIL light (also called the CEL, for Check Engine Light) is just like a kid in class waving their hand frantically because they know the answer to your question. In other words, all it means is that the engine controller has detected a problem that should be looked into. Your car knows something that you don't and the only way for you to learn what your car knows is to ask it. You need to scan your car for DTCs (Diagnostic Trouble Codes). Any auto parts store should be able to scan your car and find the fault code. Once you know that fault code, post it here and we might be able to help.

MILs can be caused by hundreds of different problems. Some are simple and easy to fix and some are serious problems. The important thing to know is to find out what is wrong quickly. Some problems can be ignored for a long time, but some problems can cause other very expensive problems if ignored for too long.

If you are still under warranty, get your car to a dealer ASAP. If not under warranty, I would suggest that you see if someone with VCDS lives near you.

Have Fun!

Don

Does the auto parts store have the VCDS? We have an autozone nearby if they can get me the codes to post I will run and do that. Is there a difference between the autozone scan and a scan done by someone with a VCDS?


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I just noticed that your car is now HOME. Good for you.
What Don said is right on. Autozone scan is more generic than VCDS, which is programmed specifically for VW products.

Maybe it's time to find a local TDIClub member with VCDS? You'll get a more complete answer that way.

Good luck.

(EDIT: my fingers are slower than tdiatlast so much of this has already been said )

Your VW speaks two diagnostic languages:

- generic On-Board Diagnostics (OBD2), as required by law for all vehicles since the mid-90s
- proprietary VW-Audi

Generic scanners, like the ones Autozone has, speak OBD2. VCDS is the best and most inexpensive way to speak VW... the other option being very expensive VW scanners.

Luckly there's a fair amount of overlap between the two systems... so a generic scan at Autozone will probably give you a good start.

There's also a list or two on this board of people with VCDS, by region... so you might be able to track someone down in your neighbourhood.

Actually the car is at its former home.... Home is now Maine. I forgot to update the profile.... So I will at least start with the Autozone scan as it will not hurt anything and will at least give us some info.


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Sounds like a good plan.

Otherwise you're just throwing internet guesses at it... and that can get expensive.

I will post them back here later today... I have been trying to find the list of people with VCDS by area but no luck yet. I'm not sure if I am looking in the right spot.


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Farmskis said:

I will post them back here later today... I have been trying to find the list of people with VCDS by area but no luck yet. I'm not sure if I am looking in the right spot.


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Click to expand...

http://forums.tdiclub.com/showthread.php?t=296841

Have Fun!

Don

Thanks for the above! Autozone code kicked out a p205b. That was the only code.


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I'm afraid it might not be good news, if you are out of warranty. Read here: http://forums.tdiclub.com/showthread.php?t=413026&highlight=p205b

HaveFun!

Don

I just have been searching around... Not good at all likely. Question is can it drive back to Maine? If it is a temp sensor then likely that turns on the heater when needed. I know the temp will remain above freezing so I am not worried about needing the heater.


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Farmskis said:

Question is can it drive back to Maine? If it is a temp sensor then likely that turns on the heater when needed. I know the temp will remain above freezing so I am not worried about needing the heater.

Click to expand...

I am afraid that I do not know the answer to this question. I know what the DEF tank is for, but I do not know what will happen (or what will not happen) if this error code is present. If it prevents DPF regenerations, I would definitely not drive from Georgia to Maine. However, if is just a warning to tell you the heater isn't working - I do not know. It might be worth a call to a VW dealer (but there is a good chance that they do not know as much about this as some people here). Let's hope that someone who better understands the CKRA's emissions system will add more information.

Have Fun!

Don

I agree if it stops regens then the dpf would definitely clog up on the drive and leave her stranded. Now if it just runs the heater it would more than likely be fine as long as regen occurs. Unless the liquid freezes and prevents urea from getting into the regen system.


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Well that doesn't really help you fix anything. They already had it scanned and got a code. Are you just shilling for the site?

Farmskis said:

I agree if it stops regens then the dpf would definitely clog up on the drive and leave her stranded. Now if it just runs the heater it would more than likely be fine as long as regen occurs. Unless the liquid freezes and prevents urea from getting into the regen system.


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Click to expand...

DEF is downstream of DPF, therefore doesn't affect regens, unless there's an electronic lock-out that just prevents you from running the engine.

That's the scary part. If the DEF system throws a code, will it ultimately prevent you from starting the engine, the way it does if you've run out of DEF (after numerous warnings, of course!)?

The light comes with no warnings or messages of any sort. We got the car back up to Maine with no issues. The light remains on but still no messages after 1100 miles. So I would hope if it was going to lock it out and prevent from starting it would say so first.


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So I had the mli light checked out and the dealer is saying both the def pressure sensor and def temp sensor needs replacing. Total cost of 1800 dollars. Each sensor is 700 dollars or so. I am kind of skeptical that both sensors would fail exactly at the same time. Are these sensors related in such a way that if one fails the other will go as well? He also said that we might be able to put it all back together and it may work fine?! So 1800 dollars for some parts the vw dealer does not even know what they do?! So I am trying to get a little more insight on how to fix this.


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I just talked a little more with the mechanic and the two part numbers he is suggesting to replace are (561-198-969 and 561-198-970 control module and pressure sensor and pump and heater kit). When we had the p code ran it gave us a p205b(temp sensor) but the dealer said that there was a p204b (pressure sensor) stored as well. Unfortunately no extended warranty and it is out of the power train. Also emissions will not cover the parts. Anyone else run into this problem with these sensors?


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I thought the adblue was considered a part of the emissions equipment? Perhaps I was mistaken.

Edit:

"To help protect our environment, some Volkswagen TDI models are now fitted with AdBlue® emissions control equipment which cleans exhaust gases helping cars to comply with the new EU6 exhaust emissions regulations."

http://www.volkswagen.co.uk/technology/diesel/adblue

Volkswagen even says it is on their site. I would assume considering this verbiage that it would be covered under the longer period emission equipment warranty. If the part fails, the vehicle would no longer meet an emission standard, I assume this as it may be different for the US vs. the UK, so you may need to check if this indeed will cause your specific vehicle to fail emission standards here in the US.

It is part of the emissions equipment just not in terms of the covered warranty equipment. The dealer told me it woke not pass emissions without the items I am replacing which to me would seem to fall under the emissions equipment and should be covered.

I guess the caveat is that there are many options on how to get the car to pass emissions and if the manufacturer wants to try a more complicated way to achieve a passing result it can do just that but they must cover the parts under a different warranty, like the oem warranty.


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