Good to hear I did run across some moe information on the problem for others that visit this post.
If there is no engine light but you pull out codes.
If there are no pending codes, then the light bulb burn out.
The code P0172 means rich, we may agree tha rich fuel has caused catalytic to glow.
The fuel pressure is normal.
The MAF (Mass Air Flow) Sensor is dirty or faulty need to be checked and cleaned.
There could be a vacuum leak.
Inspect all vacuum and PCV hoses, Clean the MAF sensor. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling Inspect fuel lines for cracks, leaks, or pinches Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced. Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)
Camshaft timing is incorrect, or the engine has an oil overfill condition EVAP vapor recovery system failure (may be pulling vacuum) Fuel pressure regulator is damaged or leaking HO2S element is contaminated with alcohol or water MAF or MAP sensor values are incorrect or out-of-range One of more fuel injectors is leaking '
" OSS ground circuit open
" OSS ground circuit short to ground
" OSS signal circuit open
" OSS signal circuit short to ground
" Park-neutral switch code present
" PCM defective (OSS signal ckt def)
" Powertrain Control Module defective
" OSS harness intermittent defect
Most likely it's a bad OSS. The OSS is located on the back of the transmission.
Wednesday, November 18th, 2009 AT 1:28 AM