P0651 CHEVROLET - 5 Volt Sensor Reference 2 Circuit
Faulty Engine Control Module (ECM)
ECM harness is open or shorted
ECM circuit poor electrical connection
Shorted sensor on 5 volt circuit
When is the code detected?
The Engine Control Module (ECM) has detected the sensor 5 volt reference circuit voltage is higher or lower than expected
Engine Light ON (or Service Engine Soon Warning Light)
P0651 Chevrolet Description
The control module has 2 internal 5-volt reference buses called 5-volt reference 1 and 5-volt reference 2 . Each reference bus provided 5-volt reference circuit for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to the reference bus. The control module monitors the voltage on the 5-volt reference buses.