Egr fault P0401

[andrew butler]

Had this fault come up last month and checked out by AA vw specialist, it's ran ok for 850miles and now back up.... obviously have searched and understand it's insufficient flow but took a pic of the values on his test and wondered if the readings give any indication that a flush may help..? Or is it just replace or map out...? A local vw indie has quoted £1450 saying that the pipes need doing at the same time to qualify for the 2 year warranty.... help opinions greatly appreciated

 

[mmi]

wondered if the readings give any indication that a flush may help..?

Difficult to say anything definite. It depends how "hard" the deposits in EGR cooler are.
What's engine code - something like CXGB, CXHA, etc. - found on configuration sticker under dash by steering column.
What's the mileage?

The test procedure seems to be the same as in thread -

[T6_measured] 01-Engine - Built-in test for EGR

So it seems - inevitable P0401. Well, visited a VW garage to be tested - the van had accumulated 30 events in ECU's memory since July 2021 (since 20 months now). Eventually managed turn on the emission light at event number 31 - thus had a priviledge to have EGR flow tested. The result -...

www.t6forum.com

 

[andrew butler]

The engine is CXFA and miles 85k...

 

[mmi]

Thanks for confirming it's EU6 (AdBlue) engine.
I guess it depends - the flush might help for some time but I'm afraid it won't last long.
@Dellmassive had his EGR flushed a few times...

 

[andrew butler]

I got a quote from Darkside Developments and they said to just replace the egr valve and not the cooler..? Is this normal.?

 

[mmi]

Hmmm... I would say that the test and especially the code most likely relate to EGR cooler.

For EGR valve not operating properly I would expect to see code P046C

EGR Valve Self Test Procedure (IDE00242)- P046C?

So, I've been getting the all too common P046C fault code along with P2457 (Insufficient EGR Cooling Performance). Neither alone will flag a check engine light but combined they sometimes seem to. To try to figure out what is going on, I ran an EGR Flow test on VCDS using instruction from @mmi...

www.t6forum.com