Expert: Roland Finston - 1/3/2012

Question
Hi,
I have a 2004 Chrysler pacifica over the last few months I have put a lot of mo.st into the car because my mechanic said I needed the work but now I'm not so sure the check engine light is on I took it by and it read 2 codes the first one was p0038 Nd the other was p0132 I have recently replaced the rear o2 sensor , motor mounts and some kind of fan module thing I have no.idea what else to do ....please help.
Thanks ,
Rachel

Answer
Hi Rachel,
If those codes are not stale, i.e. logged into the memory prior to replacing the rear oxygen sensor and which should have been erased by briefly disconnecting the - post clamp from the battery*, but rather are "new" logged in since that replacement, then you should return to the mechanic and ask that the rear sensor and labor that you paid to have done be re-done at no cost so that the repair is actually accomplished. These codes are exactly pointing to that same sensor being at fault. It may well be that the wire harness or plug is faulty or the sensor is faulty, but in any case the sensor is not working properly. There appears that one or more of the fragile wires that are attached to the sensor are shorted (touching) one another and those codes asy that the voltage reading on both the heater wire and signal wire are at incorrect values which can only be due to wires that are touching or disconnected. If the mechanic needs to know the connection of the wires to the engine controller to check this out please let me know and I can give him the specific connections and the procedure to trouble shoot these codes so he can check out the reason. But this should be done under warranty at no cost.
Roland
*You could carefully remove the - post clamp from the battery to erase the code and then see if the check engine ligth returns. The battery is located in the front of the engine compartment on the driver side. Besure to note the - post as that is the safe one to touch with a metal wrench.