Injection Pump Fuel Metering Control A Low (Cam/Rotor/Injector)
P0253 indicates the fuel injection pump metering control system is operating below expected parameters. This code typically appears on diesel engines when the fuel pressure regulator (FPR) sensor circuit detects a voltage or signal that is too low, suggesting a wiring fault, sensor failure, or PCM communication issue.
What You Might Notice
- Check Engine Light illumination
- Decreased fuel economy
- Rough engine idle
- Reduced engine power or hesitation
- Difficulty starting the engine
Most Common Causes
- 1
FPR Sensor Signal Circuit Short to Ground
A short to ground in the wiring harness between the fuel pressure regulator sensor and the PCM causes the signal voltage to drop below the expected threshold.
- 2
Open or Damaged FPR Sensor Power Circuit
A broken wire or poor connection in the power supply line to the fuel pressure regulator sensor prevents proper operation and signal transmission.
- 3
Failed Fuel Pressure Regulator Sensor
The FPR sensor itself may be defective, producing an out-of-range signal or no signal at all to the engine control module.
- 4
Corroded or Loose Electrical Connectors
Oxidation or improper connections at the FPR sensor connector or related harness connectors prevent reliable signal transmission.
How to Diagnose It
- 1
Check FPR Sensor Signal Circuit Short to Ground — A short to ground in the wiring harness between the fuel pressure regulator sensor and the PCM causes the signal voltage to drop below the expected threshold.
- 2
Check Open or Damaged FPR Sensor Power Circuit — A broken wire or poor connection in the power supply line to the fuel pressure regulator sensor prevents proper operation and signal transmission.
- 3
Check Failed Fuel Pressure Regulator Sensor — The FPR sensor itself may be defective, producing an out-of-range signal or no signal at all to the engine control module.
- 4
Check Corroded or Loose Electrical Connectors — Oxidation or improper connections at the FPR sensor connector or related harness connectors prevent reliable signal transmission.
How to Fix It
- 1
Inspect and Repair FPR Sensor Wiring
Check the entire wiring harness from the fuel pressure regulator sensor to the PCM for cuts, corrosion, or damage. Repair or replace damaged sections and ensure all connections are clean and tight.
- 2
Replace Fuel Pressure Regulator Sensor
If wiring tests pass but the signal remains low, replace the fuel pressure regulator sensor with a new OEM or quality equivalent part.
- 3
Check PCM Connector and Grounds
Inspect the PCM connector pins for corrosion or damage, and verify engine ground connections are clean and secure. Poor grounding can cause signal transmission issues.
- 4
Consult Technical Service Bulletins
Check for manufacturer TSBs specific to your vehicle model year, as P0253 may be a known issue with a documented fix or software update from the OEM.
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