Injection Pump Fuel Metering Control "B" Low (Cam/R)
The PCM has detected a discrepancy in the signal voltage supplied to the electronic fuel control actuator and the signal returned from the fuel metering control sensor. This code pertains exclusively to diesel powered vehicles. If this code is presented in a vehicle powered by any other propulsion system, suspect a defective PCM.
Code Set Parameters
If the PCM input signal from the fuel metering control sensor does not coincide with the voltage reading of the fuel control actuator driver signal, this type of code will be stored and a malfunction indicator lamp may be illuminated. Certain models will require multiple failure cycles before commanding the malfunction indicator lamp on, others will illuminate the malfunction indicator lamp on the initial failure.
Symptoms associated with a code of this type may be as minor as only a stored code and/or illuminated service engine soon lamp to as severe as a hard or no-start condition, excessive smoke from the exhaust, engine misfire, or engine hesitation especially upon acceleration.
Common causes include a dirty or clogged fuel filter, a defective fuel pump, open or shorted circuits or electrical connectors between the fuel control actuator and the PCM, or a faulty fuel control actuator driver in the PCM.
Techs report that the injector pump or injectors are frequently replaced in error when this code is presented. More often than not, the fuel filter is at fault. Shorted or open wiring and/or connectors are also found to be defective more often than injection pumps.
- Like gasoline engines, diesel engines are controlled using a PCM and other varied controllers
- In most applications, the PCM provides the fuel control actuator with a voltage signal before fuel is injected into the cylinders
- Additionally, a sensor in the fuel rail, fuel injection pump, or fuel pressure regulator inputs a voltage signal back to the PCM
- The PCM uses this input signal to monitor fuel pressure, volume, pulse width, and other delivery information
- The sensor is typically a pressure variable resistor that allows the input voltage signal to the PCM to increase as fuel pressure builds
- The PCM reads the voltage variations as fuel pressure and/or volume
- It then calculates the data and initiates the necessary adjustments in injector pulse width, engine timing, and fuel delivery.
A scanner or code reader, a digital volt/ohmmeter, and a fuel pressure gauge will be helpful in successfully diagnosing potential causes of this code.
Begin your diagnosis with a visual inspection of system circuitry, components, and electrical connectors
- If you find items that appear to have been damaged, corroded, contaminated, or disconnected, repair or replace as necessary and retest the system.
Next, connect the scanner or code reader to the vehicle and record any stored codes and freeze frame data
- This information could be crucial in diagnosing this code and may be lost when the codes are cleared
- Clear the codes and test drive the vehicle to see if the code is reset
- If the code fails to reset, you may have an intermittent condition that will be virtually impossible to correctly diagnose
- In some instances, the condition may need to be allowed to worsen before a true diagnosis can be performed
- Of course, if the vehicle is suffering from a no-start condition, this does not apply.
If the code (or drivability condition) persists, begin by testing fuel pressure and delivery volume
- Compare your findings with manufacturer’s specifications
- If fuel pressure is not found to be sufficient, remove the fuel filter and inspect for dirt and debris
- Replace the filter as necessary
- If the filter has been recently replaced or the contents are clean, test the fuel pump to make certain that it is operating with the ignition switch in the run position
- If it is not, check fuel pump voltage and ground circuits and replace the pump if battery voltage and ground are present
- For further assistance on testing the fuel pump see the diagnostic strategy for P0313.
If fuel pressure coincides with manufacturer’s specifications, test the fuel metering control sensor
- Follow manufacturer’s specifications for testing sensor resistance at varying degrees of pressure and replace the sensor if it fails to comply.
Should the sensor check out, test circuit resistance and continuity between the fuel injection control driver (in the PCM) and the fuel controller, between the fuel metering control sensor, the fuel controller, and the PCM
- Be sure to disconnect electrical connectors at the respective controllers prior to performing continuity and resistance tests with the digital volt/ohmmeter
- Failure to do so may result in damage to the controllers.
If all sensors and circuits are in-line with manufacturer’s specs, suspect PCM or fuel controller failure