Originally posted by kas:
....Was I hosed on the o2 sensors, it cost $160 a piece to have them replaced?? ...


Unfortunately, yes. Most of the times, when a CEL appears, they will just recommend changing the O2 sensor even though it might not be the reason. P0172 is Bank 1 being rich. It might do you good to pick up a scanner (or code reader) as it will save you money on needless repairs in the long run. They cost from $75 up.

From TSB,
P0172 - System Too Rich (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The code sets when the adaptive fuel tables reach a lean calibrated limit.

Fuel System:
�· Excessive fuel pressure
�· Leaking/contaminated fuel injectors
�· Vapor recovery system concern

Base Engine:
�· Oil overfill
�· Cam timing concern
�· Low cylinder compression
�· Excessive engine wear

Powertrain Control System:
�· PCM concern

Induction System:
�· MAF contamination

I suspect your MAF could have being contaminated due to an oily K&N filter. You should try cleaning the MAF and the oily K&N filter (or putting a regular paper air filter) to see if the CEL code goes away.

MAF sensor cleaning

http://www.contour.org/mods/mods.php?s=howto&displayid=36
and
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=zetecmaint&Number=989728&page=&view=&sb=5&o=&fpart=1&vc=1
and
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1b/cb/25/0900823d801bcb25.jsp

"Always do the cheap and easy ones first." 1996 V6 ATX 96K miles