P0259 - Injection Pump Fuel Metering Control B High (Cam/Rotor/Injector)
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
DTC P0259 is triggered when the Engine Control Unit (ECU) detects a high voltage condition within the fuel metering control 'B' circuit. This typically refers to the actuator or solenoid (Inlet Metering Valve) on the high-pressure fuel pump that regulates the volume of fuel entering the pumping chambers. A 'High' condition usually signifies a short circuit to battery voltage or an internal failure in the solenoid where the duty cycle feedback from the ECU does not match the actual current draw, potentially leading to over-pressurization of the fuel rail.
Possible Causes
Faulty fuel metering solenoid (Inlet Metering Valve) on the high-pressure pump
Wiring harness issue (short circuit to voltage in the signal line)
Connector corrosion or poor pin tension at the fuel pump actuator
Internal Engine Control Unit (ECU) driver failure
Symptoms
Recommended Solution
- Visual Inspection: Check the wiring harness and connectors leading to the fuel metering valve for signs of chafing, heat damage, or corrosion.
- Resistance Test: Disconnect the solenoid and measure the internal resistance. Typical values range from 1.5 to 15 Ohms depending on the manufacturer. An 'OL' reading indicates an open circuit.
- Signal Testing: Verify reference voltage with a multimeter. Use an oscilloscope to monitor the Pulse Width Modulation (PWM) signal from the ECU during cranking or engine operation.
- Component Replacement: If wiring is verified and the solenoid fails electrical tests or does not respond to active command tests via a scan tool, replace the metering valve or high-pressure pump assembly.
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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