I have a 2004 Nissan Frontier pickup that I bought used in 2012. Shortly after I purchased it the the check engine light came on, would go off and back on. Last year (before inspection) I hooked it to the diagnostic auto scanner and it read the error as four oxygen sensors. The truck was running fine but in order to get it inspected I ended up changing all four sensors. The light came back on within the week (as soon as it rained) then would go off a few days later. Rain–on, then off. I managed to get it in for inspection on one of the days the light was off. So, now it is again inspection time. Light is on, still error on the scanner as oxygen sensors. Light has not gone off in a long time.
Also noting here that I have checked this error on several different scanners. I am not spending $800 again when I really don’t think this is the problem. The truck is running fine.
Before I take it to the dealership is there anything else this could be? Thanks for any help!