My son's car is shooting a code for P0155 bank 2 sensor 1. We've changed the o2 sensor, checked fuses and wiring, replaced gas cap, and the engine coolant temp sensor. We can not get this code to go away. Any insight to other things that could trigger this code?? Need emissions inspection done on it asap and it currently won't pass.

 

Year and model?

George

 

While I am waiting for that info, that code is for the O2 sensor heater circuit which does involve the sensors heater coil but also the power and ground sources as well as the wiring and pcm control, not just the sensor. After year and model I can help you with diagnosis.

George

 

2002 Blazer LS

 

The PCM has determined that it takes too long for the O2 sensor on the passenger side in front of the cat to come up to operating temp. This cause for this is either:

1. Exhaust leak
2. Bad sensor heating element
3. Bad wiring to the sensor heater
4. Poor quality power or ground being supplied by the PCM
5. PCM failure

I would check for exhaust leaks and then test the heater circuit by unplugging the connector on the sensor and placing an old school incandescent test light across the lt grn and lt grn/wht harness wires and seeing if you get a solid strong test light at key on.

George