Injection Pump Fuel Metering Control B Range/Performance Injector)
P0257 indicates the engine control module has detected a problem with the injection pump fuel metering control system, specifically related to the fuel rail pressure (FRP) sensor circuit or the pump's ability to maintain proper fuel pressure. This code typically appears in diesel engines and suggests either an electrical circuit fault in the FRP sensor or a mechanical issue with the fuel injection pump's metering control.
What You Might Notice
- Check engine light illuminated
- Decreased fuel economy
- Rough idle or engine hesitation
- Reduced engine power or performance
- Difficulty starting the engine
Most Common Causes
- 1
FRP Sensor Circuit Fault
Open circuit, short to voltage, or short to ground in the fuel rail pressure sensor signal wire. This prevents the ECM from accurately monitoring fuel pressure.
- 2
Fuel Rail Pressure Sensor Failure
The FRP sensor itself may be defective or providing inaccurate readings to the engine control module.
- 3
Injection Pump Metering Control Malfunction
The fuel injection pump's internal metering valve or rotor may be worn, stuck, or unable to properly regulate fuel flow.
- 4
Fuel Supply or Pressure Regulation Issue
Low fuel pressure, fuel filter blockage, or faulty fuel pressure regulator preventing adequate pressure for proper metering control.
How to Diagnose It
- 1
Check FRP Sensor Circuit Fault — Open circuit, short to voltage, or short to ground in the fuel rail pressure sensor signal wire. This prevents the ECM from accurately monitoring fuel pressure.
- 2
Check Fuel Rail Pressure Sensor Failure — The FRP sensor itself may be defective or providing inaccurate readings to the engine control module.
- 3
Check Injection Pump Metering Control Malfunction — The fuel injection pump's internal metering valve or rotor may be worn, stuck, or unable to properly regulate fuel flow.
- 4
Check Fuel Supply or Pressure Regulation Issue — Low fuel pressure, fuel filter blockage, or faulty fuel pressure regulator preventing adequate pressure for proper metering control.
How to Fix It
- 1
Inspect and Test FRP Sensor Circuit
Check the fuel rail pressure sensor wiring harness for damage, corrosion, or loose connections. Use a multimeter to test for continuity and proper voltage. Repair or reseat connections as needed.
- 2
Replace Fuel Rail Pressure Sensor
If the sensor circuit tests good but the code persists, replace the fuel rail pressure sensor itself as it may be providing faulty readings.
- 3
Inspect Fuel Filter and Pressure Regulator
Check fuel filter condition and replace if clogged. Test fuel pressure with a gauge and verify the pressure regulator is functioning correctly. Replace components as necessary.
- 4
Service or Replace Injection Pump
If all electrical and fuel supply components test good, the injection pump metering control mechanism may require professional service or replacement. This typically requires specialized diesel fuel system expertise.
Need a deeper diagnosis?
Search for related repair guides or browse by system.