Mine is sorted as well after full service, EGR valve and throttle body was cleaned.
fingers crossed it has been 3 days now without any warning lights and the car runs much much better!
Hi,
I just spotted this thread and thought I might share my experience of the same fault.
I also had the following:
17559 - Long Term Fuel Trim Additive Air; Bank 1; Range 1
P1151 - 35-10 - System too Lean - Intermittent
with my 1.4 AUA petrol. In addition to the logged fault, the engine warning light would come one after a variable period after a reset (e.g. 1-3 days) depending on how much the car was used. The car also idled at too slow an RPM when warm.
The cause was (many) air leaks causing the fuel mixture to be too lean. The is a measuring block value (sorry cannot remember which one) which shows the correction percentage that the ECU is applying to the fuel mixture. If that is out of range for a while, the fault is logged. It has to be out of range for a period before the fault is indicated so the light won't go on straight away after clearing.
The majority of the air leaks were caused by a cracked plastic oil separator and associated cracked hoses. The hole in the oil separate also produced a large oil leak which resulted in unexpectedly high oil consumption! Once these were fixed, the idling was OK but although the system was much better, it was still slightly too lean and outside the accepted range which mean that the fault was still being recorded.
Tracking down the last air leak was tricky, the whole inlet side was checked for leaks and gaskets changed. The problem turned out to be the gasket on the non-OEM EGR valve that was fitted during previous ownership. A genuine Audi gasket was installed which was a different design (it had an additional sealing flange) and this cured the problem. Its been running for 2 years without this issue since.
regards
Andrew