Engine Management Light - Costly issues building.....

Hi guys,

Long time lurker, rarely a poster as you seem to have always answered my questions already...!

However, I have a problem that is starting to cost some dosh, and I would like advice -

Audi A3 2.0TFSI (8P). Purchased (New) in 2007 and a Revo (Select) remap straight away. Now has 63k on the clock.

The Engine management light has been coming on intermittently, and initially came on after a "Full to the brim" fuel up. Shortly after this, the light came on, would go out after a while but would soon come back on.
The code it throws is P0420 (Emissions) and I have looked at the threads here about it.

The car has now had a new EGR valve and also a new Secondary coolant pump. Went about 250 miles before the light came back on.

Now for the interesting stuff -

Audi are saying that as it has been remapped, this may be causing the "Tolerances to have been exceeded". It has been remapped for the last 7 years and 60,000 before this issue. While I can see that tolerances may be getting close, so suddenly?

Secondly, I had a serious fuel contamination issue (Filled up with fuel and there was 150ml Water in the 300 ml fuel drawn off). Needless to say, engine died and luckily no damage (Pulled over as soon as the engine sounded "Rough" and it didn't start again. Audi wanted £2.5k to replace the entire fuel system but I ran it through the insurance. The assessor came back and wanted just the fuel filter replaced and the system flushed. (Cost £300 and less than my excess) this worked and the car has been fine since (water contamination was only there for a matter of a day or so...).

Audi are now saying they are going to replace the Charcoal filter as a good will gesture (as the EGR valve did nothing) but that the problems could be due to the fuel contamination and / or the Remap.

Two questions - What else in the system would throw an emission light? (P0420) and secondly, what chances of the remap causing this fault after 6 years and 60,000 miles of fault free driving since it was done?

Thanks Guys (& Girls!!).

G

Thanks Guys,

Dan - I've looked at the codes and like you, and leaning towards something other than the Fuel system - O2 Sensors sound quite plausible......

Shadow - I too doubt the Remap has anything to do with this at all. After all, why? How could it? (Surely the change in the fueling / emissions post remap will have been immediate and then not change since - why / what has / could change now?)


With the Revo Select I am able to "revert" to stock map and then back again. Recently I forgot to do so and on a road test the mechanic apparently commented on how quick it was and that he had not driven one like it....this prompted the question "has it been chipped" and I had to come clean (a bit bleeding obvious when compared to stock....!!

I could understand the fuel contamination causing an issue with the Cat / sensors, but shortly afterwards, the car happily did 2000 miles without the light on, suggesting that unless the Cat is an intermittent fault (and how could it be?) then it is something else more "Mechanical / electrical" perhaps....???

Thanks for the input guys - appreciated.

G

Veedub - Thanks for that, but with the Lambda sensors being £80 ea, I would prefer for make sure they are faulty before speculating (And I don't have a Oscilloscope, or the knowledge to use one....(I'm a lawyer....!!).

I've been thinking about Stage 2. The trouble is, this is DSG and I already get wheel slip in every gear up to 3rd (sometimes 4th) if I floor it and without turning off the ESP and buying tyres every month, I am not sure I would get that much benefit from it (apart from a few more points....!!!).

Cheers,