I was drivinghome and going up a hill under full throtle and the code P0171 showed up . Car a 2005 JCW ran well after clearing code. Does anyone have an Idea as to what might have caused the code? BaD GAS, WATER IN THE fuel ,to much ethanol in fuel. Code is SYSTEM TO LEAN. aNY IDEAS WOULD BE HELPFUL.

 

I could have sworn I had the same code thrown, but it turned out to be the cam timing sensor.

 

If it's reporting a too lean condition, it means there is too much oxygen in the system. This could be a bad/dirty MAF sensor, a leak in the system after or near the MAF, or a clogged injector/filter/fuel line.

 

R53's don't have MAF's...

 

Sorry, MAP sensor.

 

my 04 had the same fault for a while. i took it it in at work and used the smoke leak tester and oddly found that the o-ring for the oil fill cap was leaking air into the system. i replaced the cap and have not had the light come on yet.