PDA

View Full Version : 2001 S8 - 16558 (P0174) Fuel Trim



s8.
04-02-2008, 07:57 PM
Hi,

A few weeks ago my S8 recorded DTC 16558 (P0174), System too lean - Bank 2.

I have looked at the Long Term Fuel trims and Bank 1 is 9 and Bank 2 is 15, showing that Bank 2 is way lean and now out of tolerance. The reading from both precat O2 sensors look to be in the normal ranges, 0.1 - 0.8 v.

Given that both banks use the same MAF, I looked for a vacuum leak introducing unmetered air to Bank 2 and replaced all the vacuum hoses and both inlet mainifold gaskets. No difference.

The car starts first time, everytime, no obvious lack of power or stumbling, leading me to think it's perhaps not fuel pressure/volume related.

The only symptom is a slightly rough idle. Not sure where to go next on this.

Any thoughts appreciated.

Cheers,