Engine Performance problem
2003 Chevy Truck V8 Four Wheel Drive Automatic 93000 miles
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My emission Control llight came on and I took it by the local auto zone. The PCM determinined a malfuntion exist for oxygen sensor 1 in bank 1. I called the Dealer and they want over $700 dollars to replace them. They said I need four. I checked the local NAPA store and found the sensors only run about $50. I can only locate two on the truck. one just above the cat on the drivers side and one below the cat. Where can I find the location of the other 2?