[Black Grouse]

It may be worth checking all previous service documentation that the correct grade of oil has been used, VW 507.00 ACEA-C3, as not using "low SAPS" oil WILL fill the DPF with ash prematurely. This won't resolve the present issue but prevent it occurring again.

 

[SaVAGeSoot]

Gents, without being able to see specifics you are jumping to conclusions. It won't cost me anything, so if you want to replace DPFs or whatever on a whim, go for it.

Pay for VCDS and see for sure what you have. The DPF won't clog to a level that it needs to be replaced that early. The system went into limo mode to prevent that and many other very expensive failures. You need proper tools to see what the ECU is being presented with which makes it step in to take preventative action.

 

[SDJ077]

Thank you all for your suggestions and advice - much appreciated. We just got the report back from the dealer's diagnosis. Basically they're stating that the issue is the G31 mass air flow (maf) sensor, which is malfunctioning and not telling the DPF to regenerate when it needs to. So, they're going to be replacing the MAF sensor and then doing a forced regeneration. They reckon that will solve the issue.

 

[Black Grouse]

That sounds like BS - the MAF sensor doesn't initiate DPF regenerations, the pre- and post-DPF sensors are used for that.

 

[SaVAGeSoot]

It isn't BS. The MAF is one of the many system components which needs to provide correct data in order to make things be fully autonomous. Without the system knowing how much air it's sucking in initially, it cannot continue to function as intended.

 

[Black Grouse]

It isn't BS. The MAF is one of the many system components which needs to provide correct data in order to make things be fully autonomous. Without the system knowing how much air it's sucking in initially, it cannot continue to function as intended.

Yes, I know what the MAF does - but it's not used to determine if DPF regenerations are needed.

 

[SaVAGeSoot]

I repeat... it is one of the "inputs" needed to determine the soot loading

 

[SDJ077]

Thanks everyone for your advice and suggestions. We got the MAF sensor replaced and the forced regen done earlier this week. The car seems to be working fine now. Best of all, it was covered under the extended warranty - which was awesome.

 

[SaVAGeSoot]

Imagine that!
Glad you got a good end result.

 

[77 K20]

Too late for that, when that light for dpf comes up don't turn the engine off but instead go for a hard run to clear it off.
If you turn off the engine then it will likely go into limp mode and forced regen is the only way...

I wish I would have knows this yesterday... "Don't turn the engine off but instead go for a hard run to clear it off".

I went out to lunch yesterday at work. Coming back to work the DPF light came on with a message to check the owners manual. I couldn't be late getting back to work so just figured after work I'd go for a nice hour long drive up a long hill to burn the DPF clean. Right after work I started the Touareg. DPF light is on. Drove out of the parking lot and within 50 yards onto the main road the DPF light turned off and the glow plug light started flashing instead. Limp mode. No power. The dealer was just 2 miles away vs me driving 16 miles home. Took to the dealer. They gave me a loaner car for the rest of the week. With the Thanksgiving holiday they can't look at it until next week.

It has been in the single digits here for temperature. I saw a big cloud of "steam" out of the exhaust as it was trying to do a regen last week. It didn't finish. The next day I drove 35 miles in sport mode or manually shifted to keep RPMs up. Guess that wasn't good enough.

 

[SaVAGeSoot]

I wish I would have knows this yesterday... "Don't turn the engine off but instead go for a hard run to clear it off".

It's not always that easy... that only works when everything is OK and you've just repeatedly interrupted active regen attempts.... if you have failed system components, you can run it hard all you want.... it won't "clear off".