S4 amber engine warning light

[JohnP68]

I have a warning light on my B6 S4 dash. Engine appears to be running ok. Vag-com shows the following error codes:

VAG-COM Version: Release 409.1-US

Control Module Part Number: 8E0 910 560
Component and/or Version: 4.2L V8/5V 0040
Software Coding: 0011711
Work Shop Code: WSC 12595
2 Faults Found:
17535 - Fuel Trim: Bank 1 (Mult): System too Rich
P1127 - 002 - Lower Limit Exceeded
17537 - Fuel Trim: Bank 2 (Mult): System too Rich
P1129 - 002 - Lower Limit Exceeded

I've also logged blocks 2 and 32 from the Engine group, with the following results:

Block 2 is reading about 5 g's at idle, rising to around 100 g's at 7000 rpm (car in neutral)
Block 32 is reading 0, -18.8, -0.8, -18.0

Does anyone have any suggestions regarding what is wrong please?

[Mats]

Very similar to a problem I had on my S5 a month ago. Turned out to be the inlet manifold sensor and flap. I noticed that fuel consumption had dropped through the floor to around 14mpg where usually it is 19-21. Idle was a little rough on start up. but car was otherwise running fine, if a little rich.

[Tame Technician]

Its running too rich, there are a multitude of things that can cause that.

The fault light comes on when the car notices it too rich (via the lambda probes) and as much as it has tried to trim down the fueling it cant trim it down enough, normal get this when the long turm fuel trim is -20% or so, which is what you have.


Things to look into.
Most important - Fuel pressure:-

Is it too high, have had a few S4's where the regulating valve has been blocked or broken and not returning enough pressure to the tank. Have even seen one where a tyre fitter jacked up on the fuel return pipe giving the car too much fuel pressure.

Mechanical blockage if intake:-
Have had rodents filling airboxes with nuts and straw (sounds far fetched I know but we see it once or twice a year) If its got manifold tumble flaps are they moving freely, are the vacuum actualors that move they ok. etc

Any sign of corrosion on the lambda probe connectors causing faulty rich reading.

[JohnP68]

Tame Technician said:

Its running too rich, there are a multitude of things that can cause that.

The fault light comes on when the car notices it too rich (via the lambda probes) and as much as it has tried to trim down the fueling it cant trim it down enough, normal get this when the long turm fuel trim is -20% or so, which is what you have.


Things to look into.
Most important - Fuel pressure:-

Is it too high, have had a few S4's where the regulating valve has been blocked or broken and not returning enough pressure to the tank. Have even seen one where a tyre fitter jacked up on the fuel return pipe giving the car too much fuel pressure.

Mechanical blockage if intake:-
Have had rodents filling airboxes with nuts and straw (sounds far fetched I know but we see it once or twice a year) If its got manifold tumble flaps are they moving freely, are the vacuum actualors that move they ok. etc

Any sign of corrosion on the lambda probe connectors causing faulty rich reading.

Thanks. I've now booked it in for the garage to look at it - I know my limits!

[Jack_and_MLE]

Tame Technician said:

Have had rodents filling air boxes with nuts and straw (sounds far fetched I know but we see it once or twice a year)

Yes I can confirmed that, in my case a squirrel which filled the passer side of the engine bay, with nuts!

Jack