1990 Montero with about 225000 miles. Driven about 1500 mi yearly. for past 10 years. Oxygen sensor replaced about 7 yrs ago. About 2 yrs ago check engine light started coming on after driving about 10 miles. (I know - why wait 2 yrs to question you - thought I could figure it out). In the habit now of unhookng negative battery cable for about 15 mins to clear codes. Then keep on driving and hope it doesn’t happen during annual inspection. Any ideas for a solution?
Yeah, why don’t you share the codes with us so we can make a better assesment of your problem?