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Re: Slow 02 response 2013 Silverado 5.3 4X4
Posted to Technical Discussion Forum on 1/24/2020

I believe it is/was koeo. This was GMs way of verifying if heater was functioning. The bias voltage of 450 millivolts would decrease if heater was working correctly. This is from memory. Please don't quote. Good luck Login to read more.