Injection Pump Fuel Metering Control B Circuit
The P0256 code means the vehicle's onboard diagnostic system has detected: Injection Pump Fuel Metering Control B Circuit. This is a critical severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- hard
- Estimated cost
- $200 - $800 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Engine performance severely degraded
- Possible no-start condition
- Abnormal fuel rail pressure
Probable Causes (Ranked by Likelihood)
- Faulty fuel metering control B valve Very High
- Wiring damage to metering control B High
- Fuel contamination Moderate
- PCM driver circuit B failure Low
Frequently Asked Questions
What is fuel metering control B?
Metering control B is a secondary fuel metering valve on some diesel injection systems that provides additional fuel flow control or controls a separate pump.
Is P0256 a diesel-only code?
Yes, injection pump metering codes are specific to diesel fuel injection systems.
Can I drive with P0256?
No, fuel metering control faults can cause engine damage from incorrect fuel pressure and delivery.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Read fuel metering control B PID on scan tool.
-
Measure metering valve B resistance and compare to spec.
-
Inspect wiring and connector for damage.
-
Command metering valve B with scan tool and monitor fuel rail pressure response.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- 2010-2020 Ford F-350 (6.7L Diesel)
- 2012-2019 Ram 3500 (6.7L Cummins)
- 2008-2018 Chevrolet Silverado 3500 (6.6L Duramax)
- 2011-2020 GMC Sierra 3500 (6.6L Duramax)
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