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2004 Blazer

My Check Engine light comes on whenever the car idles - even if just at a traffic light. Had it put on a diagnostic machine at the local garage and it showed that it was an oxygen sensor. Replaced both sensors and the first time I let it idle the light came on again. Any ideas? I did find that sometimes if I removed and replaced the gas cap it would make the light go out. Sometimes the light just goes out for no reason. I tried calling the show, but after an hour of busy signal just gave up.

Try cleaning the gas cap gasket and gas filler neck really well, It worked for me though it took about a week for it to go out, how many miles and what maintenance? as it could be air filter fuel filter spark plugs related.

We don’t want to assume the same code keeps getting set, that would be a mistake. Have you ever thought of getting a personal code reader?