- Mar 14, 2007
The SES light came on. I checked it. It was PO155. Bank 2 Sensor 1 heater circuit malfunction. The heater wires on the sensor showed no continuity. I replaced it. Next up came PO138. Vehicle ran fine. I thought great, another sensor is bad. I cleared the code. It has not come back however, the PO155 comes back all the time now. I keep clearing it and it comes right back. I checked the new sensor and the heater circuit is ok. I checked the other upstream sensor. Heater wires have continuity. Ok, maybe it's the vehicle wires. I put my meter on the vehicle side of the harness on the terminals corresponding to the heater circuit. When I turn the key to the run position. I get system voltage. This happens on both upstream sensors. I could just replace the one I haven't replaced since I have a brand new Bosch for it on hand. I really hate being a parts changer and the old sensor has continuity just like a new one. Should I just replace it and see what happens?