Sensor Reference Voltage "B" Circuit/Open
The DURAMAX-P0651 (Duramax) diesel fault code means: Sensor Reference Voltage "B" Circuit/Open. This is a moderate severity code.
- Keep driving?
- Yes, with caution
- DIY difficulty
- intermediate
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What Are the Symptoms of DURAMAX-P0651?
- Check Engine Light on
- Several sensor codes at once
- Possible reduced power or hard starting
What Causes DURAMAX-P0651? (Most Likely First)
- A shorted sensor on the shared reference circuit High
- Damaged wiring or connector on the reference circuit High
- Engine computer fault Low
Can I Still Drive with DURAMAX-P0651?
Yes, with caution. DURAMAX-P0651 is rated moderate severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does P0651 mean on a Duramax?
P0651 means Sensor Reference Voltage "B" Circuit/Open. The engine computer has detected a fault on reference voltage circuit "B", the supply it shares with several sensors.
Is P0651 a Duramax-specific code?
No. P0651 is a generic OBD-II code defined by SAE J2012, so it means the same thing on any vehicle that sets it. The exact conditions GM uses to set it on its diesels are in GM service information.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose DURAMAX-P0651?
Find which sensors share reference "B" in the service information.
Unplug those sensors one at a time and watch whether the reference voltage recovers.
Inspect the shared wiring for chafing or shorts.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines P0651 as a generic OBD-II code)
P0651 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:
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