Injection Pump Fuel Metering Control B High (Cam/Rotor/Injector)
P0259 indicates the engine control module detected a signal voltage that is higher than expected from the fuel injection pump metering control circuit. This typically occurs in diesel engines where the injection pump's rotor/cam position sensor or fuel rail pressure (FRP) sensor is sending an out-of-range high signal to the PCM.
What You Might Notice
- Check engine light illumination
- Decreased fuel economy
- Rough idle or stumbling during acceleration
- Possible loss of power or sluggish performance
- Potential white or black smoke from exhaust
Most Common Causes
- 1
Failed FRP Sensor
The fuel rail pressure sensor may be malfunctioning and sending consistently high voltage signals to the PCM, triggering the code.
- 2
Short to Power in Signal Circuit
A wiring fault causing the FRP sensor signal wire to contact power, resulting in an abnormally high voltage reading at the PCM.
- 3
Open Ground or Power Circuit at FRP Sensor
A break or poor connection in the power supply or ground wire to the fuel rail pressure sensor can cause erratic high voltage readings.
- 4
Corroded or Damaged Connector
Oxidized or physically damaged electrical connectors on the FRP sensor or related circuits can create high resistance and voltage irregularities.
How to Diagnose It
- 1
Check Failed FRP Sensor — The fuel rail pressure sensor may be malfunctioning and sending consistently high voltage signals to the PCM, triggering the code.
- 2
Check Short to Power in Signal Circuit — A wiring fault causing the FRP sensor signal wire to contact power, resulting in an abnormally high voltage reading at the PCM.
- 3
Check Open Ground or Power Circuit at FRP Sensor — A break or poor connection in the power supply or ground wire to the fuel rail pressure sensor can cause erratic high voltage readings.
- 4
Check Corroded or Damaged Connector — Oxidized or physically damaged electrical connectors on the FRP sensor or related circuits can create high resistance and voltage irregularities.
How to Fix It
- 1
Replace Fuel Rail Pressure Sensor
Disconnect the FRP sensor electrical connector and remove the sensor from the fuel rail assembly. Install a new OEM or quality replacement sensor, ensuring proper torque specifications and connector seating.
- 2
Inspect and Repair Wiring Harness
Visually inspect the FRP sensor signal wire and power/ground circuits for damage, corrosion, or pinching. Repair or replace any damaged sections of the wiring harness and ensure all connections are clean and tight.
- 3
Clean or Replace FRP Sensor Connectors
Disconnect the FRP sensor connector and inspect for corrosion or damage. Clean contacts with electrical contact cleaner and dielectric grease, or replace the connector assembly if pins are damaged.
- 4
Test PCM and Check for Technical Service Bulletins
After repairs, clear the code and perform a test drive to verify resolution. Check manufacturer TSBs for your specific vehicle model, as some vehicles have known issues with this code requiring software updates rather than hardware replacement.
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