First of all, what car doub have, model n year and also engine, but in any car u can test the O2 sensor with a scan tool all u need to do is monitoring the bad sensor raving the engine at wide open throttle but before u do this make sure the engine is warm up,(about 15 mnts running) every time u do that the O 2 sensor should go rich,if not u have to check the wiring for opens,shorts to ground .....
Answers & Comments
First of all, what car doub have, model n year and also engine, but in any car u can test the O2 sensor with a scan tool all u need to do is monitoring the bad sensor raving the engine at wide open throttle but before u do this make sure the engine is warm up,(about 15 mnts running) every time u do that the O 2 sensor should go rich,if not u have to check the wiring for opens,shorts to ground .....