What it means
Injection Pump Fuel Metering Control B Low (Cam/Rotor/Injector): the control module has detected this fault condition. This affects fueling of the associated cylinders.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Injection-pump fuel metering control B regulates fuel delivery, and the control module monitors its electrical signal and operation. P0258 sets when the control B signal is below the expected range. A low signal can prevent the pump from responding correctly and disrupt fueling.
Common causes
Most likely first.
- Damaged wiring or connector
- Fuel metering actuator or valve B failure
- Poor electrical connection
- Control module fault
Symptoms
- Check-engine light on
- Hard starting or no start
- Rough running
- Reduced engine power
How to diagnose it
- Record freeze-frame data and check live metering and fuel-pressure information to see whether control B drops low during cranking, idle, or load.
- Inspect control B's connector and wiring for a short to ground, damaged insulation, corrosion, or loose terminals.
- Check the fuel supply and filter for restriction or air entry that could accompany the low-signal fault.
- Measure the control B circuit using vehicle wiring information and compare results with the manufacturer's specification.
- Test the metering actuator and control-module output before replacing either component.
Common fixes
- Repair wiring shorted to ground or damaged control B harness sections.
- Clean, repair, or secure corroded or loose connector terminals.
- Replace a failed fuel-metering actuator or valve B after circuit checks pass.
- Repair the control module only if its output is confirmed faulty.
Can I keep driving?
Do not continue a trip if the engine stalls, will not start reliably, or has severe power loss; it could stop unexpectedly. If symptoms are mild, drive only gently to a nearby repair location and avoid towing or hard acceleration.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.