Contour Enthusiasts Group Archives Forums General Troubleshooting BANK 2 LEAN

If it were a hard fault (constant) then the light would return immediately. The fact that it comes on only after exercising the engine indicates that it is either intermitant or that certain driving conditions must be met.

If you have the ability to read the oxygen sensors while driving, clear the codes then road test and see if you can tell what is going on when the light returns.

Big Jim which O2 do you think it is? I know bank 2 is the radiator side, but PO174 is upstream or downstream? Pardone my ignorance.

Hey, man.. Jim just did a VERY thorough explanation.. read up on what he just wrote out.

Upstreams are the ONLY sensors that determine a:f ratios.. downstreams determine catalyst efficiency.

If you think that your code IS from a faulty sensor (and not that your car is actually lean) then it would be the UPSTREAM sensor, on that bank.

A downstream fault would trigger a catalyst below efficiency code.

Ray

got it, its the upstream. did a search on the code. think it might be my freshly oiled k+n. so i cleaned maf with contact cleaner and wiped off the bottum of the cone filter. so we'll see if thats it. hopefully i dont go through what others have.