P0258 Injection Pump Fuel Metering Control B Low (Cam/Rotor/Injector)

P0258 points to injection pump fuel metering control B low. The B control signal is grounded, missing voltage, or below expected range.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace injectors or rails before correcting the low fuel metering control B circuit.

Symptoms of P0258

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0258

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Measure control B voltage, feed, ground, resistance, and current while checking for short-to-ground or missing-feed conditions.
Inspect pump connector pins, harness routing, terminal corrosion, fuel contamination, fuse supply, and module driver output.
Compare the low circuit event with fuel pressure, injection timing, engine hesitation, no-start, and freeze-frame voltage.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.