My car's check engine light On and Off

[Jamesc]

One of my cars failed annual inspect for exhaust.

My mechanic just changed the spark plugs and clean the O2 sensor.

Then it passes.

If O2 is the reason for CE light, give it a clean first before replacing.

Maybe no need to replace.

Edited September 29, 2022 by Jamesc

[lieflatonthefloor]

he failef cos of cel or cos of thr smoke come our the emisson rod say too high?

[lieflatonthefloor]

how to clean the o2 btw?

[Jamesc]

.

Edited October 3, 2022 by Jamesc

[Jamesc]

Clean rag and some quick dry alcohol

Actually my mechanic used a dirty rag but it still solved the problem.

55 minutes ago, lieflatonthefloor said:

how to clean the o2 btw?

 

[Jamesc]

Spark plug also no need to change.

Brush off the carbon and check gap is correct size.

[Yeobh]

@lieflatonthefloor 

Get your mechanic to clean up the catalytic  convertor, just remove the o2 sensor  and spray in the degreaser detergent into the catalytic convertor.