Technical Description of OBD-II Trouble Code
The high injection pump fuel metering control A (Cam/Rotor/Injector) is a generic powertrain/engine diagnostic trouble code that can apply to all diesel fueled OBD-II equipped engines. It is more commonly found in certain Mercedes Benz and VW vehicles, but can also occur in Ford, Chevy, GMC, Ram, and other vehicles. The specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
The injection pump metering control circuit “A” is typically located inside or on the side of the injection pump, which is bolted to the engine. This circuit consists 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 uses this voltage signal to determine the amount of fuel to put into the engine based on the operating conditions. The P0254 trouble code is set when the voltage at the FRP sensor stays above a certain level for too long. This code is usually considered an electrical circuit issue.
The severity of this DTC is not severe because the PCM can compensate adequately for the electrical failure.
Some symptoms of the P0254 code may include the malfunction indicator lamp (MIL) illumination and a decrease in fuel economy.
Common causes of the P0254 code may include a short to power in the signal circuit to the FRP sensor, an open in power or ground at the FRP sensor, a failed FRP sensor, or a failed PCM.
Troubleshooting steps for the P0254 code may include checking for technical service bulletins (TSB) for the vehicle, visually inspecting the FRP sensor and its wiring for any damage, cleaning the terminals of the connector, clearing the diagnostic trouble codes from memory and checking if the code returns, testing the FRP sensor and its associated circuits with a digital voltmeter, and considering the replacement of the FRP sensor or PCM if necessary.
