Any ideas on this? I've done the "just in case" gas cap check and didn't help. It's a 98' K1500. New fuel pump assembly about two months ago and has been fine since. I believe the sensor was part of that whole assembly. Got it at Advance Auto Parts. Yesterday started the service light and today got it read and the code came back as PO453. They read it twice. The first time it had three codes in it, two PO453 (how that works I don't know) and one PO452. A high and low voltage code in there at the same time. They were able to clear the one PO453 and the PO452 but the one 453 wouldn't clear. They said they have never had a code not clear before. So, the light is on and it has the one 453 code in it that won't go away. Any ideas? What would cause a high voltage code other than a defective sensor? Last but not least, can I replace just the sensor or do I have to take out the whole assembly again and replace it. It's covered under warranty but what a pain. Thanks.