Q: I'm driving a 2.3L four cylinder '93 Isuzu pickup. The O2 light lit up on the dash. I changed the oxygen sensor, but the light did not go out. Does this mean that the new sensor is no good? Is there another way of turning off the light?
A: The O2 sensor lamp on your Isuzu is simply a maintenance reminder that's part of the instrument-cluster assembly and comes on every 90,000 miles to tell you it's time to replace the oxygen sensor. Since you've already replaced the sensor, we can tell you how to turn the light off. This one isn't as easy as most and involves more than just depressing a hidden button. If you think you can handle the job of removing and installing the instrument cluster then follow these instructions--if not, find someone who can. Once the cluster has been removed, turn it around, keeping it upright, and observe the rear face. You should see a screw with a "KSW" mark next to it. To the right of the screw you'll see a piece of masking tape covering an empty hole with the same "KSW" marking. We'll refer to the one on the left as hole A and the one on the right as hole B. Remove the masking tape from hole B, then remove the screw from hole A and install it in hole B. Finish up by placing a new piece of masking tape over the empty hole A. This will reset the O2 service reminder for another 90,000 miles. If you pass 180,000 miles and the light is bothering you again, then simply reverse the above procedure.
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