why does my check eng. light come on then go off

Question

2002 Chevy 1500 check engine light comes on and is on for two or three days then goes off and stays off for a week then comes back on . I have replaced all the sensor and it stayed off for four monthes . Could the sensors be bad again?

Answer 1

P0155 is only for Bank 2 Sensor 1, you can try to clean the sensor and see if that fixes the issue. you may have a wiring issue or PCM might be bad (see info below)