P0258 Injection Pump Fuel Metering Control B Low
OBD-II Trouble Code Technical Description
Injection Pump Fuel Metering Control B Low (Cam/Rotor/Injector)
What does that mean?
This generic powertrain/engine diagnostic trouble code can typically apply to all diesel fueled OBD-II equipped engines (e.g. Ford, Chevy, GMC, Ram, etc.), but shows up more often in certain Mercedes Benz and VW vehicles.
Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
The Injection Pump Metering Control Circuit "B" is usually found mounted inside / on the side of the injection pump bolted to the engine. The Injection Pump Metering Control Circuit "B" is usually made up of a Fuel Rack Position (FRP) Sensor and a Fuel Quantity Actuator.
The FRP sensor converts the amount of diesel fuel being delivered by the Fuel Quantity Actuator to the injectors into an electrical signal for the Powertrain Control Module (PCM).
The PCM receives this voltage signal to determine how much fuel it will put into the engine based upon engine operating conditions. This code is set if this input does not match normal engine operating conditions stored in the PCM’s memory, even for a second, as this diagnostic trouble code demonstrates. It also looks at the voltage signal from the FRP sensor to determine if it is correct at initial Key On.
The code P0258 Injection Pump Fuel Metering Control B Low (Cam/Rotor/Injector) is set when the voltage at the sensor stays below a set level (usually under 0.3V) for too long a period. This code is usually considered to be an electrical circuit issue. Refer to a vehicle specific repair manual to determine which is the "B" part of the circuit for your particular application.
Troubleshooting steps may vary depending upon manufacturer, type of FRP sensor and wire colors.
What is the severity of this DTC?
Severity in this case will be not severe. Since it is electrical failure, the PCM can compensate adequately for it.
What are some of the symptoms of the code?
Symptoms of a P0258 trouble code may include:
Malfunction Indicator Lamp (MIL) illumination Decrease in fuel economyWhat are some of the common causes of the code?
Causes for this P0258 code may include:
Short to ground in the signal circuit to the FRP sensor - possible Short to ground or open in the power circuit at FRP sensor - possible Failed PCM - unlikelyWhat are some P0258 troubleshooting steps?
A good starting point is always to check for technical service bulletins (TSB) for your vehicle. Your issue may be a known issue with a known fix put out by the manufacturer and can save you time and money during diagnosis.
Next, locate the FRP sensor on your vehicle. This sensor is usually found usually found mounted inside / on the side of the injection pump bolted to the engine. Once located, visually inspect the connector and wiring. Look for scraping, rubbing, bare wires, burn spots or melted plastic. Pull the connector apart and carefully inspect the terminals (the metal parts) inside the connector. See if they look burned or have a green tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning of the terminals is needed. Let dry and apply electrical grease where the terminals contact.
If you have a scan tool, clear the diagnostic trouble codes from memory, and see if P0258 code returns. If it does not, then the connections were most likely your problem.
If the P0258 code does return, we will need to test the FRP sensor and its associated circuits. With the Key Off, disconnect the electrical connector at the FRP sensor. Connect a Digital Voltmeter black lead to the ground terminal at the FRP sensor wiring harness connector. Connect the red lead of the Digital Voltmeter
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