P0643 Chevrolet Sensor Reference Voltage A Circuit High

Possible causes

– Faulty Engine Control Module (ECM)
– ECM harness is open or shorted
– ECM circuit poor electrical connection
– Shorted sensor on 5 volt circuit

What about the obd code?

The Engine Control Module (ECM) has detected the sensor 5 volt reference circuit voltage is higher than expected

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)