Wiring fault in the metering control circuit, such as a short to earth, high resistance or chafed insulation; Poor connection or corroded terminals at the pump or fuel metering valve connector; Faulty fuel metering valve or solenoid on the injection pump; Low or unstable supply voltage due to a weak battery or poor earth; Internal fault in the injection pump, including worn cam, rotor or injector-side components, as the code description suggests; Fault in the engine control unit driver circuit for the metering control; Fuel supply problem such as restricted filter or air in the system affecting pump response.

P0258

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

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
58: FaultThe specific fault in that area

What it means

P0258 is a generic powertrain code meaning the control unit has detected a low signal or fault in the 'B' fuel metering control circuit of the injection pump on a diesel engine. The control unit commands the metering device to deliver a set amount of fuel and sets the code when the circuit voltage, current or feedback is lower than expected. What 'B' refers to (a second metering valve, a second pump or a second circuit) depends on the engine and pump design.

Symptoms

Engine cranks but is hard to start or does not start
Loss of power or limp mode
Rough idle or stalling
Engine misfire or surging under load
Engine management warning light on
Reduced or uneven fuel delivery under acceleration

Possible causes

Wiring fault in the metering control circuit, such as a short to earth, high resistance or chafed insulationlikely
Poor connection or corroded terminals at the pump or fuel metering valve connectorlikely
Faulty fuel metering valve or solenoid on the injection pumplikely
Low or unstable supply voltage due to a weak battery or poor earthpossible
Internal fault in the injection pump, including worn cam, rotor or injector-side components, as the code description suggestspossible
Fault in the engine control unit driver circuit for the metering controlrare
Fuel supply problem such as restricted filter or air in the system affecting pump responserare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including engine speed, load and battery voltage
Check for related codes, especially other fuel metering, rail pressure or sensor supply codes, and diagnose those in a logical order
Visually inspect the wiring and connector at the injection pump and metering valve for damage, chafing, oil contamination, corrosion or loose pins
Check battery condition, charging voltage and the main earth connections
Test the metering valve circuit for supply, earth and continuity against the manufacturer's wiring diagram, and look for shorts to earth
Measure the metering valve resistance and compare it with the specification for that engine
Use live data to compare commanded and actual fuel metering or pressure values, if the model supports it
Check fuel filter condition and low-pressure supply to rule out fuel starvation, following the model-specific procedure

How to fix

Repair or replace damaged wiring and clean or renew corroded or loose connector terminals
Replace the fuel metering valve if its resistance or operation is out of specification, where it is serviced separately
Repair the battery, charging or earth faults that cause low voltage
Replace or recondition the injection pump if internal wear or a fault is confirmed
Replace the fuel filter and correct any low-pressure fuel supply faults
Replace or repair the control unit only after the wiring, supply and actuator have been fully proven good

Can I keep driving?

High severity

Avoid driving the car if it is running poorly, losing power or stalling, as fuel delivery problems can cause a loss of control and may harm the pump. Have it diagnosed promptly before further use.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.