P0250 - Injection Pump Fuel Metering Control "B" High (Cam/Rotor/Injector)
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0250 is set when the Engine Control Module (ECM) detects a high voltage condition in the fuel metering control 'B' circuit. This specifically refers to the circuit controlling the fuel quantity actuator (solenoid) on the injection pump. The ECM monitors the feedback signal or the current draw of the actuator; a high voltage signal typically indicates a short to battery voltage in the wiring harness or an internal failure of the solenoid itself. The 'B' designation refers to a specific area of the pump's internal timing or a secondary metering valve depending on the manufacturer's design.
Possible Causes
Short to voltage in the fuel metering actuator wiring harness
Faulty fuel metering solenoid (internal short)
Corroded or loose connector at the high-pressure pump
Internal Engine Control Module (ECM) failure
Symptoms
Recommended Solution
- Visual Inspection: Check wiring harness and connectors at the injection pump for chafing, melted insulation, or corrosion.
- Voltage Test: Measure voltage on the control circuit with ignition ON. A constant battery voltage reading where a toggled signal is expected indicates a short to power.
- Resistance Test: Disconnect the actuator and measure internal resistance. Normal values are typically 1-5 Ohms. High resistance or an open circuit indicates a faulty solenoid.
- Oscilloscope Analysis: Check the PWM (Pulse Width Modulation) signal from the ECM. If the signal stays high regardless of load, investigate the ECM driver circuit.
- Component Replacement: Replace the fuel metering valve/solenoid if internal electrical specs are out of range.
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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