Hey guys. CEL came on today on my way home from work. The code was p0138. I just replaced the 02 sensors in november. My air/fuel gauge looks about the same as it was before the CEL. I dont know where to start. I'm planning to reset the computer and see if it comes on again, any ideas after that would be helpful. It rained like crazy here today, but i only drove about 1/2 of a mile and no big puddles or anything...would it throw that code if i got water in the intake?
Thanks!

Originally posted by LeakyMitsu
would it throw that code if i got water in the intake? Thanks!

Probably not. Is there an existing warranty on the o2 sensor?

there might be, i have no idea. its a bosch sensor. i think the haynes manual said that it was "downstream heated 02 sensor-shorted to voltage".
im not really even sure what the hell that means?

might be a shorted O2 sensor, if it wasn't sealed properly water might have gotten in the connector, car running ok? if it's just the downstram O2 all that does is check and make sure the cat's working fine. pull the connectors apart. hit them with some brakleen and then put some dielectric grease on the pins and put it back together. reset the computer (if you are doing your electrical work properly You'd have pulled the battery cable and caused the ecm to reset anyway)

Shorted to voltage means that the sensor wire has a short in it somewhere with another wire that's got positive voltage.

Unplug the downstream o2 and check the harness for voltage on the sensor wire going to the ECU.

If there's an existing warranty on the o2, replace it and see how it does.