Check Engine Light code P1055
I got a check engine light come on and the code was P0155. This is an “Upstream Heated Oxygen Sensor Heater HTR 21 Circuit Malfunction Bank 2”. Reading about this a lot of times if it just this code it is usually a bad ground wire and not necessary the O2 sensor. I looked up the location and it is the O2 sensor on the left side of engine upstream of catalytic converter. I went under the truck to take a look and sure enough I could see immediately what the problem was. This is because of the length of the O2 sensor and how the wires come out of the top of the sensor, the transmission shifter cable was rubbing on it. The space is such that the cable literally runs along the top of the O2 sensor rubbing against the wires of the O2 sensor. In fact, the O2 sensor wires had rubbed into the sheathing of the transmission shifter cable. Due to where the O2 wires had rub exposing the bare wire, it was impossible to fix and just easier to replace the sensor but rerouted the transmission shifter cable below the O2 sensor.
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I have 86,000 miles so it took some time for this but hopefully this will help someone else out.









