Injection Pump Fuel Metering Control B Circuit Low
The P0257 code means the vehicle's onboard diagnostic system has detected: Injection Pump Fuel Metering Control B Circuit Low. 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 illuminated
- Engine may not start or stalls
- Fuel pressure too low
- Severe performance loss
Probable Causes (Ranked by Likelihood)
- Short to ground in metering control B wiring Very High
- Internally shorted metering control B valve High
- Corroded connector Moderate
- PCM driver B shorted Low
Step-by-Step Diagnostic Procedure
-
Measure metering control B resistance. Below spec indicates short.
-
Check wiring for short to ground.
-
Disconnect valve and verify code changes.
-
Inspect connector for fuel contamination.
Frequently Asked Questions
What causes circuit low on metering control B?
A short to ground in the wiring or an internally shorted solenoid valve is the most common cause.
Can fuel leaks cause P0257?
Yes, fuel leaking onto the wiring or connector can degrade insulation and cause shorts to ground.
Is this code related to the fuel filter?
Not directly, but a clogged fuel filter can cause the metering valve to work harder, potentially accelerating wear and failure.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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