MOT failure on emmissions??? Help

[Bigandbald]

Ok so my standard 111,000 mile S3 just failed the MOT on Emmissions. the MOT tester said it was the Lambda sensor but before i go and buy one i just want to make sure it is that and not something else??

Anyone got any ideas??

 

[superkarl]

thrash it and try again

 

[<tuffty/>]

AFR is at 0.96 from that printout.. you would need to check blocks 032, 031 and 001 initially to see what the ECU thinks is happening...

Also check for fault codes... adaption may not be working for some reason... this normally happens if the N249 or post cat lambda is disconnected...

<tuffty/>

 

[aragorn]

There could be multiple issues, have you checked for fault codes?

First Fast idle test to me looks like the cat isnt working. The Lambda and HC reading is fine, but CO is typical of a decatted car.

Second fast idle test has gone quite rich, which could mean an airleak, faulty lambda, duff MAF or various other issues.

Natural idle again looks like the cat isnt working.


With a working cat, CO is typically almost 0.

 

[Bigandbald]

Tuffty...you appear to be the VCDS God here, unfortunately i dont have it and have posted on here before asking for help and no one responded??? happy to pay for someone's time to plug it in and diagnose.

i had thought about maybe an additive in the fuel or something???

 

[<tuffty/>]

As Aragorn said... could be one of a few things... VCDS or at the very least a generic code reader required really to see if the ECU is unhappy...

Check for split pipes under the inlet manifold... clue will be oil... oil should be in the engine not on the outside... if its outside then its leaked from somewhere...

If the garage you had the MOT at has a smoke tester it would be a good idea to get that done as this should highlight split pipes more easily

<tuffty/>

 

[jamiebennett81]

OR

Take it to a very friendly MOT tester.....

 

[aragorn]

OR

Dont, and fix the issues so the engine is actually running properly.

 

[Bigandbald]

OR

Dont, and fix the issues so the engine is actually running properly.

MO was jut going to say I can get it through the MOT that's not the problem, but I'm all up for fixing it as my MPG is shocking at best so happy to resolve the issue(s) but need it diagnosed.

anyone know anyone near Basingstoke with vagcom that wants to earn some beer tokens???

 

[jamiebennett81]

MO was jut going to say I can get it through the MOT that's not the problem, but I'm all up for fixing it as my MPG is shocking at best so happy to resolve the issue(s) but need it diagnosed.

anyone know anyone near Basingstoke with vagcom that wants to earn some beer tokens???

Prawn can help as he is in Basingstoke or I can as I'm Reading based

 

[Bigandbald]

Ill try to get hold of Prawn, if not ill pop you a pm if thats ok.

many thanks peeps!!!

 

[Bigandbald]

PRAWN............HELP!!!!!!!!