On my Discovery II SE 2003, we were having an intermittent on and off of the light. Codes were checked by my mechanic and he was showing exhaust leak. Exhaust leak was fixed with new gasket and headers had no cracks in them. O2 sensor was replaced but when replacing it was noted the factory plug was missing and the wiring had been spliced together. Not done under my ownership of the vehicle. Spliced in factory plug and replaced sensor found no sensor activity. Suspect one wire has a short to ground causing check engine light to flag. It is suspected the fault is behind cylinder head or under intake. At this point I thought I would just live with it. Check Engine light continues to stay on. How much time could be spent finding this problem ? I want to try to get it operable without major reconstruction.

 

To not spend more money getting a diagnosis, take truck to a major auto parts store, where they usually read codes for free. Write down numbers, post back here.

 

Did you have the codes cleared after they were read? Most of the codes will not clear on their own, you have to use the scan tool to clear them.

It seems like you're saying the problem is still with an exhaust leak. If the codes come back after clearing them, then the quickest thing is to test it with a smoke machine. The machine blows smoke up the tail pipe (since you're looking for an exhaust leak), then you use light to look for the smoke coming out, and you found your leak.

 

Make sure you get the code numbers when having them read and get back to us with those numbers.