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
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.
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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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