P2459 Issue

[tristan81491]

First CEL of owning and it's this code. I recently did a road trip with about 700+ pounds of stuff in the trunk/back seats and a bike rack on the hitch with two bikes and moved to DC. The only driving since unloading the car has been a max 20 minute drive in mostly urban stop and go. Heard the car regenning a lot during a couple of short drives but unclear whether it ever fully finished.

After doing some digging it seems like it may be a bad EGT sensor. But i also came across a thread of a dealer trying to charge over $1K to replace the thermostat which sounds ridiculous and I want to avoid that. Car is still covered under dieselgate. I have yet to let a VW dealer do any work other than engine oil/filter and transmission oil/filter and being in a new place, unclear whether I should A: clear the code and get the car on the highway for a bit to let it run a full regen at decent speed and see if the check engine light comes back or B get an appointment to get it looked/fixed under dieselgate. Would clearing the code and it coming back run me into issues with coverage under dieselgate?

The issue is that I am planning a 15-hour round trip this weekend and unclear whether the car will be regenning too much or I can just wait until after the trip to have the car checked out by VW.

Thanks all!

 

[AverageAndy]

You may want to try cleaning out the tubes leading to the DPF pressure sensor. Check out this thread:

P2459/08863 DPF Regeneration Frequency | TDIClub Forums

 

[Tom in PT]

I would just clear the code and motor on. That is what I did and the code never came back. I think it was triggered by the a lot of short trips after the car initiated a regen and it did not have a chance to complete a regen after X number of start/stop cycles. That is my theory anyway. You might consider replacing the pressure sensor for the DPF (top of engine, passenger side) or better yet putting in a Kerma tune. I just did that and my frequent regens are in the rear view mirror (knock on wood).

Once you hit the highway and drive about 10 miles you have driven enough to complete any regen from my experience.

Cleaning the tubes as mentioned in the above post might be a fix but in my case it turned out to not be the root cause.

 

[Tom in PT]

Also, if you clear the code and it does not come back - no reason to invoke Dieselgate warranty anyway.
If you clear the code and it does come back - invoke the warranty (if still available).
If you go to the dealer who knows what will happen - they may have the car months of longer if they say it needs a new DPF - unavailable at the present as I understand it. I wanted to avoid a dealer visit.

 

[tristan81491]

Thanks! Cleared code, drove almost 900 miles and no issue so far

 

[tristan81491]

An update: Check engine light came back then went off after doing some highway driving. It appears it is still doing more frequent regens though.
Brought it in to the dealer with the check engine light off and they could not replicate the issue and told me to bring it back as soon as it gets a check engine light again.

 

[Tom in PT]

I hope your dealer can resolve the frequent regen issue. I am of the belief that the frequent regens are bad on many counts - cooking the coolant, overheating the associated plastic parts and shortening their life, clogging the heater core, etc etc. and if your dealer can't fix it once and for all (throwing expensive parts at it in the process) then get a Kerma tune and this problem will end.

 

[oilhammer]

A bad pressure sensor, or a leak or obstruction in the lines to it, could also cause the ECU to get false readings as to the current DPF load conditions.

 

[tristan81491]

I hope your dealer can resolve the frequent regen issue. I am of the belief that the frequent regens are bad on many counts - cooking the coolant, overheating the associated plastic parts and shortening their life, clogging the heater core, etc etc. and if your dealer can't fix it once and for all (throwing expensive parts at it in the process) then get a Kerma tune and this problem will end.

I agree with the belief that the frequent regens are bad on many counts. I am hoping I do not end up with a clogged heater core. Would love to delete but I am at 145K and would rather wait until after the warranty period.

A bad pressure sensor, or a leak or obstruction in the lines to it, could also cause the ECU to get false readings as to the current DPF load conditions.

I would love to swap in a new sensor but I believe I need VAG COM to set adaptations? I will take a look this weekend to see if I can open check the hoses for any blockages.

If I were still in Iowa City, I would bring it down to you Oilhammer to look at it! Thanks again for a great job on the timing belt service in May!

 

[tristan81491]

Ok so code came back and I decided to get VCDS. Ordered it yesterday and got it today which was awesome.

I haven’t yet pulled the hose to see if anything is in there as per OilHammer’s recommendation I saw in another post but I have been looking to get a VCDS cable for a while.

I was able to Auto Scan and get a bunch of info. I am pasting what I believe to be the relevant section but can post the rest if needed:


1 Fault Found:
8863 - Diesel Particulate Filter
P2459 00 [232] - Regeneration Frequency
MIL ON - Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 234690 km
Date: 2023.01.08
Time: 16:04:34

Engine RPM: 1041.00 /min
Normed load value: 0.0 %
Vehicle speed: 26 km/h
Coolant temperature: 36 °C
Intake air temperature: 21 °C
Ambient air pressure: 1020 mbar
Voltage terminal 30: 14.200 V
Unlearning counter according OBD: 40
Exhaust gas jet volume in particle filter: 41.2 m³/h
Particl.filt.: different.press.sensor 1 bank 1: adaptat. value: 27 hPa
Particle filter: soot mass measured: 22.46 g
Particle filter: soot mass calculated: 22.46 g
Particl.filt.: differential pressur.sensor 1 bank 1: dyn.offset: 0 hPa
Particulate filter input: temp. sensor 1: bank 1: raw value: 178.5 °C
Particulate filter output: temp. sensor 1: bank 1: raw value: 111.4 °C

Readiness: 1 1 0 0 0


On a slightly unrelated note this was my first VCDS experience and I kept getting errors “no response from controller” when I tried to go into specific modules. Some modules like engine and transmission work but when I tried to go into central electronics to enable window down with key fob I got that error. Will keep trying different things but it was able to auto scan and get the important stuff for now.

 

[oilhammer]

Go to the Autoscan part, and get the Gateway Installation list, that will display what all modules your car has.

 

[tristan81491]

Thanks! That makes sense now; I assumed all the modules listed under modules were available but after looking through the gateway installation list it was pretty clear I was trying to access modules that are not on the car.

I will pull the hoses to the DPF sensor and see if I am able to blow through them. I searched in vain for the sensors last week only to realize they were inside a buttoned up heatshield pocket thing

 

[oilhammer]

Yep, we call those 'space blankets'.

 

[740GLE]

So I wonder if the nipple area was already weak and was the original issue, you just did it in. Toss # in the part in any vendors site and if a newer version is out there it should be flagged as replaced only last digit changing.

In a pinch you could drive around a little bit if you plug off that sensor port so no exhaust gasses start melting anything, i'd only do this if you absolutely needed to drive some place.

No need to replace both sensors unless you just want to sleep a little better and change both of them "while your there".

 

[oilhammer]

I believe it is cheaper to buy the whole assembly, bracket and all, with both sensors. Don't ask me why.