P0258: Injection Pump Fuel Metering Control B Low
The P0258 code indicates that the Engine Control Module (ECM) has detected a low voltage or signal from the fuel metering control circuit 'B' in the injection pump. This circuit is responsible for regulating fuel delivery based on engine demand. A low signal suggests a malfunction in the fuel metering actuator, wiring, or the pump itself, leading to improper fuel metering and potential performance issues.
1. Most Common Causes
- Faulty or worn fuel metering control valve (IMV/SCV)
- Control circuit wiring shorted to ground or low voltage
- Corroded or loose connections in the injection pump harness
- Excessive internal resistance in the fuel metering solenoid
- Internal injection pump failure (mechanical wear of the regulation mechanism)
- Faulty injection pump relay or control module
- Damaged ECM/PCM control output or incorrect programming
2. Symptoms You Will Notice
- Engine hesitation or surging
- Reduced power and poor acceleration
- Hard starting or stalling
- Check Engine Light illuminated
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect wiring and connectors for damage or corrosion.
Step 3: Test the fuel metering actuator resistance and voltage supply.
Step 4: Perform a fuel pressure test to verify pump output.
Step 5: If necessary, remove and bench test the injection pump.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0258 can cause poor engine performance, stalling, or even damage to the injection pump and engine.
How much does it cost to fix?▼
Repair costs vary from $150 for simple wiring repairs to $600 or more for injection pump replacement, including labor.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.