Originally Posted by LakevilleSSEi
p1640 = Controls low speed fans and something else....don't remember what right off hand.
p0171 = Lean code...just what it says.....test your o2 sensor or replace it per the hayes manual.
You can also look in tech info also for tips and pointers with these codes....pretty common ones around here I think.. I know I've had both, I still have the QDM 1 once in a while.....
There'* alot more to lean than an O2 sensor. Let'* assume that it actually MIGHT be lean, and the O2 is reading correctly. Fuel pump, filter, FPR, and injectors are all culprits.