Sensor Reference Voltage ‘A’ Circuit Low
Table of contents
P0642 BUICK Possible Causes
- Faulty Powertrain Control Module (PCM)
- Powertrain Control Module harness is open or shorted
- Powertrain Control Module circuit poor electrical connection
- Shorted or open sensor on the 5-volt circuit
How do I fix code P0642 BUICK?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Cost of diagnosing the P0642 BUICK code
The cost of diagnosing the P0642 BUICK code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0642 BUICK Description
The Powertrain Control Module (PCM) has 2 internal 5-volt reference buses called 5-volt reference 1 (A) and 5-volt reference 2 (B). Each reference bus provided a 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 Powertrain Control Module monitors the voltage on the 5-volt reference buses. The Diagnostic Trouble Code (DTC) will set when the Powertrain Control Module has detected the sensor 5-volt reference circuit voltage is lower than expected.