Fault Code P0174 anyone help?

[Condor]

I had forgotten that we had a generic fault code reader at home, so plugged it into the S8 this am to see if I could shed some light on the Engine Management Light suddenly coming on - it's given a Fault Code P0174 System too lean Bank 2, whatever that means - could one of the more knowledgeable members give me some info on this and if its serious / expensive / urgent or not?

After three weeks of no success trying to find a local Audi tech, when I realised we had the reader, I thought I'd check and see what it said........

[Nollywood]

Lazy O2 sensor, post-catalyst. Replace, clear code, and all will be well.

[ainarssems]

Originally Posted by Nollywood

Lazy O2 sensor, post-catalyst. Replace, clear code, and all will be well.

I am sorry, I cannot agree- post catalyst O2 sensor only monitors catalyst and would not throw this code but another for catalyst not functioning properly.

This could be pre cat O2 sensor, air/vacuum leak, dirty/faulty injector or cambelt timing off.

[Architex_mA8tey]

16558/P0174 - System Too Lean, Bank 2

Possible Symptoms
Irregular behaviour

Possible Causes
Fuel system
Excessive fuel pressure
Leaking or contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Air leaks after the MAF
Vacuum leaks
Improper seated engine oil dipstick
Stuck EGR valve
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near HO2Ss.

Special Notes

Also see: Fuel Trim Info

[Nollywood]

Originally Posted by ainarssems

I am sorry, I cannot agree- post catalyst O2 sensor only monitors catalyst and would not throw this code but another for catalyst not functioning properly.

This could be pre cat O2 sensor, air/vacuum leak, dirty/faulty injector or cambelt timing off.

My guy, no need to be sorry, different opinions. I had the same code on my S8, I cleared the code, but it wouldn't stay off. I replaced a post-catalyst O2 sensor, and that sorted things out.

[Condor]

Are there some things I should check which are relatively simply solved without a lot of mechanical changes?

Like could it be a fuse somewhere?
Clean the MAF sensor unit?
Change air filter?
Generally check hoses as far as possible?

I assume an o2 sensor is a lambda sensor? I did have a fault a few years ago and it was a lambda sensor which was replaced at a main dealers. If I recall it was quite a quick and easy job - is that the case?

I'd like to do as much as possible before going off to some greedy workshop somewhere - when they see a woman with a big ex-expensive car, they generally rub their hands in glee and get ready for a massive rip off

[Sub-Zero]

Leaking and split vacuum hoses mine threw up the same fault code solid engine management light ! Change hoses you will find them split I replaced and cleared the code all okay.