I have been having problems with my O2 sensor for a while now, so i finally decided to sign up here and ask.

My problem is that i am getting a P0155 code. I have replaced the sensor(i have tested to make sure it is working properly). I am having no performance issues that i can tell, and the live data i am getting from my OBDII reader shows valid and predictable responses.

I have taken it to a show to get it diagnosed and the guy says there is a short somewhere between the PCM and the sensor, as the ground wire is getting power. he tells me that the black wire is the wire getting power, but there is only one problem with that.

The 4 wires going into the sensor are orange/green/purple/pink. There are no black wires going into the sensor at all.

As of yet, i am thinking that the PCM is going out but i prefer that i don't spend that much money for a new one until i know it is a problem.

Thank you in advance for any help.

 

P0155 is the failure of the heater circuit as implied by the lengthy time to get up to operating temperature. The vehicle will run OK until the sensor gets warm enough from the exhaust. It will probably have higher emissions during the slower warm up period.

George