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My S6 has been a rolling project since I bought it! (2009). Nothing major just this and that. I have used Vagcom since early 2010 to keep an eye on the car. Since that point I have had an ongoing batch of fault codes in the Engine module. Performance on the road does not seem to be effected but now that I am using the car (I wasn't much before, just the odd 2 mile run here and there) I am noticing things can't be right as mpg is around 12-14 on average.

It has been rolling road tested since having it at PS and MRC with pretty much what it should be as the result.

Anyway these are the codes:

5 Faults Found:
16711 - Knock Sensor 1 (G61): Signal too Low
P0327 - 35-00 - -
17972 - Throttle Actuator (J338): Under-Voltage during Basic Setting
P1564 - 35-10 - - - Intermittent
16716 - Knock Sensor 2 (G66): Signal too Low
P0332 - 35-10 - - - Intermittent
17549 - Load Calculation Cross Check: Implausible Value
P1141 - 35-10 - - - Intermittent
17521 - Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent
Readiness: 0000 0000

I have studied Vagcom and ran a check on the MAF using measuring block 002. It pulled 254g/s of air or (318BHP). This would indicate the MAF is OK.
I have also ran a check on 032 (fuel trim) but the readings were 0%. This was because I cleared the fault codes which reset the trim.

Audi would probably say a fault with the module as I have 5 faults. I would discount this myself.

I believe one issue may be throwing the other faults. It is plausible that both front lambdas are down, but both lambdas and both knock sensors seems unlikely. I tested the knock sensors a while back and they were in limits.

Throttle actuator under voltage during basic setting, Elsa says to perform a TBA (throttle Body Alignment). It does say this is required if the battery is disconnected. I have had the battery off a few times but never performed a TBA. Didn't want to throw confusion into the mix by doing one now either.

I have checked and found loads of articles on separate faults. Lots of reading with no single answer for any of them. I have not found anyone who has had a combination of the five!

I think performing an adaption run and checking the fuel trims will help diagnose the MAF. I understand the limits are -/+ 3% on the first (idle) and -/+ 10% on the second. Can anyone confirm this to be the limits for the fuel trim on an S6?

I am confused as to where the Throttle actuator issue sits with all this?

I have not had the covers off recently or found any split vac pipes etc.

Any quick win ideas guys?

Is the ECU mapped? If so, who's map is it?

PhilT wrote:Is the ECU mapped? If so, who's map is it?

No it is standard!

I took it out today

Scanned for faults before taking it out.
3 faults were picked up.
1 Knock sensor signal too low
2 O2 sensors, both banks, both pre cat

Took it out, did about 40 mile across the peaks (not perfect conditions- twisties, wet, altitude, average speed cameras and slower traffic). Anyhow it's where I live so no option really.

Fuel trim started adjusting and has settled at -0.9%idle and 0.8%malt.

I did a WOT pull in 2nd to around 6900rpm. Hit 262 g/s of MAF airflow. That equates to 327.5 Bhp at 1800ft asl running on 95RON. Not too bad!

Both pre cat lambdas then!?! huhmmm