Injection Pump Fuel Metering Control B Range/Performance
The P0257 code indicates that the Engine Control Module (ECM) has detected a range or performance problem with the fuel metering control 'B' circuit in the injection pump. This typically refers to the fuel quantity actuator or metering valve that regulates fuel delivery to the injectors. The ECM monitors the actual fuel metering position versus the commanded position; if the difference exceeds a threshold, this code sets. Common causes include a faulty fuel metering actuator, wiring issues, or internal pump failure.
01. Most Common Causes
- Faulty fuel metering actuator (fuel quantity solenoid)
- Wiring or connector issues in the metering control circuit
- Internal injection pump mechanical failure
- ECM software or hardware malfunction
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine hard to start or no start
- Reduced engine power and poor acceleration
- Rough idle or engine misfire
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect wiring and connectors at the injection pump for damage, corrosion, or loose connections.
Step 3: Test the fuel metering actuator resistance and compare to manufacturer specifications.
Step 4: Use a scan tool to command the actuator and monitor actual vs. commanded position.
Step 5: If wiring and actuator are okay, suspect internal pump failure and perform fuel pressure/volume tests.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may experience loss of power, stalling, or difficulty starting, which can lead to unsafe driving conditions. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Repair costs vary widely: replacing a fuel metering actuator may cost $200-$500, while a full injection pump replacement can exceed $1,500.