Check engine light (CEL) first came on 8 months ago. Local mechanic reset the light and about every 500 to 700 miles CEL comes on again. Read-out from computer tool states, Catalytic Converter. Car has 86000 miles, oil changed every 3000 miles, get 30 mpg on highway. Had the light reset 5 days ago and went through inspection. Car passed and no problems. OK…why is the CEL coming on?
Bad oxygen sensor?
Bad catalytic converter?
The exact code number would be helpful for us to assist you. I’ll bet it was something like P0420: Catalyst System Efficiency Below Threshold (Bank 1). Here’s a good explanation of the code:
you may just need a new fuel cap, or make sure it’s tight after filling up.
OK…why is the CEL coming on?
Because the car is telling you that something is wrong and needs to be checked.
Sorry, had to say it. Listen to VDC.