I have a 2003 Ford exploreer that I had tested for bad 02 sensor and I changed both 02 sensors before the converter and the check engine light remains on .I pulled the battery negative and the check engine light turned of and while I was driving it turned on again .
This is where at home diagnosis and in-shop diagnosis diverge. A shop will begin by checking that bank for an over rich or lean condition, then moving closer to finding the problem which for example could be an injector with a bad spray pattern or leak, or a minor vacuum leak somewhere .(too many other items to mention) You can do further testing with the use of a manual and a decent digital volt-ohm meter.It takes more time and isn't always as productive but most times with a bit of research and learning on your part the problem can be found. Unless I made a lucky guess, I could spend all day writing down ideas and would not be correct.
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What would cause the check engine light to come on if it's not a sensor.The vehicle is running ok.The person at autozone put the OBD scanner and he said it was the 02 sensor bank 1.
Changing o2 sensors often does not cure a problem. The sensors are likely "seeing" an exhaust condition that is beyond their ability to read. Likely there is another engine condition that is causing this.
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