Trouble Codes: What's it mean?

[Jeffyh]

I have a '94 GT. I did a KOEO test on my car and it passed, but it gave me the CM codes:

172-C : H02S sensor fault/lean
173-C : H02S sensor fault/rich
176-C : H02S sensor fault/always lean

I don't understand, does that mean my O2 sensor is done? If it is, how do you know what side?

Also my car's being a spaz. The AODE transmission stays in gear longer that it should and shifts sporatically, but doesn't slip. And while driving, i hear a pop every now and then, and my car seems to have shut off for a split second. My car looses all power, all the gauges drop as if they were at the off position, my speakers make a popping noise, and then the car lurches slightly forward and is in normal running condition.

ANY HELP OR IDEAS WOULD BE GREATLY APPRECIATED.

 

[CManT1914]

Sounds like your O2's are going/or have gone out. You can do a resistance check on them (not real hard, but you'll need a DMM). The other issues sounds like a bad engine ground. Try checking those out. The only one I know of bolts to the engine block right in front of the oil filter. Good luck and bump.

 

[JRPony]

Well, concerning the O2 faults, a resistance check isn't going to tell you much of anything. The only real way to check an O2 sensor is to look at the voltage pattern on an osciloscope and test its responsiveness. A multimeter is too slow to respond to the voltage fluctuations and will sometimes only give you an average, which is not helpful.

For a DIY, it is hard to really condemn the O2. It is really just an educated guess. Since there are mutiple fault codes showing stuck rich and lean, I would say to just replace them.

 

[HISSIN50]

Dont forget to look for a vac leak first (well, I would).

Good luck.

 

[mo_dingo]

because 1 of the O2's is saying both rich, and lean, I would guess you have a bad o2 on the right side (whichever side that is). Replace them both and see what happens.

You need to disconnect the battery when doing this so you will reset the PCM and have a fresh start.
Scott