I understand what the Heated Oxygen Sensor Heater Circuit (P0155) is used for, but I'm wondering if anyone knows if the heater is used at times OTHER than engine cold and idle? for instance if the heater in an O2 sensor wasn't working would the sensor still perform normally cruising around 1600rpm? would the exhaust gases alone keep it at the right temperature?

 

If an oxygen sensor is not up to its operating temperature, it will not produce voltage.

At start up, the PCM turns on the heater, if the PCM does not receive a signal from the oxygen sensor within a certain amount of time, usually 2 to 2.5 minutes, the PCM will set P0155. When this DTC sets, either the heater is not working, or the PCM is not receiving a signal from the sensor, (which could be due to a bad sensor or sensor wiring). The PCM expects to see a signal from the oxygen sensor, if it doesn't, it assumes the heater is at fault. The diagnostic flow chart will instruct you to check the sensor and heater circuits, so the problem will be found. When the engine is running properly, and the coolant is at operating temperature, the oxygen sensor heater is not necessary. Some of the older vehicles don't even have a heater in the oxygen sensor.

 

That's kinda what I thought - Thank you!!!