P0258 - Injection Pump Fuel Metering Control B Low (Cam/Rotor/Injector)
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0258 indicates that the engine control module (ECM) has detected a low voltage condition in the injection pump fuel metering control 'B' circuit. This circuit typically controls a solenoid (Inlet Metering Valve or Volume Control Valve) that manages the amount of fuel entering the high-pressure pumping elements. The code is set when the return voltage or current draw is lower than the expected PWM (Pulse Width Modulation) feedback, often suggesting a short to ground or a failed solenoid coil. This fault usually triggers a limp mode to prevent uncontrolled fuel pressure.
Possible Causes
Faulty fuel metering solenoid/regulator (internal short)
Damaged wiring harness or connector corrosion (short to ground)
Faulty fuel pressure sensor providing incorrect feedback
Internal ECM failure
Symptoms
Recommended Solution
- Visual Inspection: Check the fuel metering solenoid connector for signs of fuel leakage, oil contamination, or pin corrosion.
- Electrical Measurement: Use a multimeter to measure the resistance of the solenoid coil. Normal values are typically between 1.5 - 15 Ohms (check factory specs). A reading of 0 Ohms indicates a short.
- Advanced Diagnosis: Use an oscilloscope to monitor the PWM duty cycle signal from the ECU. The signal should fluctuate based on fuel pressure demand.
- Wiring: Perform a continuity and ground insulation test on the harness between the ECU and the high-pressure pump.
- Component Replacement: Replace the fuel metering valve/solenoid and reset adaptation values using a diagnostic scan tool.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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