s10 trouble code help
 

hi, i have a 02 s10 4x4 and i keep getting trouble codes p0128 and p0138. i have changed the 02 sensor but still keep getting this code. also i have no idea what the p0128 is trying to say. i have a code reader and when i clear the codes they keep coming back. any help?

possibly a faulty cat converter.........

I had a 2001 ZR2 S-10. It would continuae to throw secondary air pump codes. The pump would suck water in due to an ill engineered design. It would leve the check engine light on but not create any problems. GM made a fix for this that had the air tube running up the fender to a higher point. That may be the code you are seeing.

code po128 and po138
 

po128 - coolant thermostat/ below thermostat regulating temperature. check your coolant level...if thats ok when your engine is cold see if the thrmostat is stuck open..if thats ok you probably have a coolant temp. sensor failure or wire or connector problem. the po138 is your oxygen sensor picking up a rich exhaust. fuel injection has no choke and has to use coolant temp. to control fuel richness on cold starts. if your coolant is not reaching a specific temp in a specific time the engine light will come on. if the coolant temp. problem is fixed the o2 sensor problem will most likely straighten out. the o2 sensor may or may not clean up with the proper air/fuel mix. hope this helps.... matt.