Firstly, I work with computers and not computers on trucks - I am not an automotive mechanic or have ever claimed to be mechanically inclined.
The check engine light is on steady. We have replaced the gas cap and changed the fuel in the tank with new high grade fuel. It's a 1997 Chev W/T 1500 2wd. It was purchased in Ontario Canada, and is now failing a NC emissions test. A mechanic has checked the truck and has indicated the problem is not the oxygen sensor - but probably some type of problem in the electrical wiring harness. Might that be a ground fault - a bad cable going to ground on the engine or frame? An intermittent fault of some type?
The truck only has ~45000 miles.
What can I check re the wiring - is there anything easy - ie. volts, ohms or current and if so where do I check?
Any other easy checks. I have a very mechanical father in law - so we can probably follow more advanced suggestions.
All advice to resolve the problem is greatly appreciated.