P0651
Sensor Reference Voltage B Circuit/Open
P0651 is an OBD-II diagnostic trouble code meaning: Sensor Reference Voltage B Circuit/Open. Common causes: open circuit in reference voltage b, short circuit to ground. Estimated repair cost: $11–556.
Symptoms
- Check Engine light comes on
- Multiple sensor codes from circuit B at the same time
- Engine limp mode
- Unstable idle
- Dips and jerks when pressing the gas pedal
Causes
- Open circuit in reference voltage B
- Short circuit to ground
- Sensor with internal short circuit, “pulling” circuit B to ground
- Damage to the wiring harness (frayed, pinched)
- ECU malfunction (rare)
How to Fix
- Read all codes - multiple sensor codes indicate a reference circuit problem
- Check 5V voltage at circuit B sensor reference pins
- Disconnect sensors one at a time to find a sensor with an internal short circuit
- Inspect the wiring harness for damage
- Check the ECU connector for oxidation and damage.
- Replace the faulty sensor or repair the wiring
Related codes
Error P0651 by Vehicle Brand
FAQ
What does the P0651 code mean?
P0651 is an OBD-II diagnostic trouble code that indicates: Sensor Reference Voltage B Circuit/Open
What causes a P0651 error code?
The most common causes of P0651 include: Open circuit in reference voltage B; Short circuit to ground; Sensor with internal short circuit, “pulling” circuit B to ground; Damage to the wiring harness (frayed, pinched).
How do I fix a P0651 diagnostic trouble code?
To fix P0651: Read all codes - multiple sensor codes indicate a reference circuit problem. Check 5V voltage at circuit B sensor reference pins. Disconnect sensors one at a time to find a sensor with an internal short circuit. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P0651?
Yes, but get it checked soon
How much does it cost to fix P0651?
The estimated repair cost for P0651 is $11–556. Actual cost depends on your vehicle, location, and labor rates.
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