P0155 is o2 sensor heater circuit malfunction bank 2 sensor 1 it is the o2 sensor circuit in front of the cat converter the o2 sensors are located mounted to the exhaust pipe in front and behind the catylic converter the problem is in the circuit [wiring or sensor itself] check wiring and repair if necessary if the short or open circuit is the sensor need to replace sensor +++ P0161 is 02 sensor heater circuit malfunction BANK 2 SENSOR 2 ++++++ this is the sensor behind the cat converter
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I have a 99 Yukon and the code for 2nd bank O2 was being tripped because the air filter was old and needed changing. It was messing up the air flow. Try putting in a new air filter or blowing out the one you have now with an air compressor. It worked for me and the light went off!
The code for O2 does not mean the senor is bad. It means the quality of exhaust coming out of the cat is bad. That can be for a number of reasons. The sensor is after the catalytic converter on the exhaust pipe. To remove you will need a special wrench and it should be hot first to make it easier to loosen up. I would check the quality of air,,etc and clean the Air Flow Meter, and throttle body first. Only use Air Flow Meter cleaner,,,NOT carb cleaner! As I said,, check your air filter out. If the engine is starving for air that will mess up the AFM etc.
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