Engine Error
P0651
Sensor Reference Voltage B Circuit/Open
Severity
High
Symptoms
Multiple warning lights, reduced engine power, hard starting
Common Causes
- Short in a 5-volt reference sensor (e.g., MAP, TPS, APP)
- Chafed wiring harness shorting to ground
- Corroded PCM connector
- Internal PCM failure
How to Fix
- 1 Unplug sensors one by one to find the shorted component
- 2 Trace and repair the 5V reference wiring
- 3 Replace the shorted sensor
- 4 Replace the PCM
Estimated Repair Cost
USD
$100
–
$1200
Sensor replacement: $100 - $300; Diagnostic labor: $150 - $300