Symptoms
Symptoms associated with engine code P2542 may include:
- Malfunction indicator light illuminated
- Inability to start the engine
- Longer than normal starting times
- Hesitation during acceleration
- Reduced fuel economy
Potential Causes
Possible reasons for this code appearing are:
- Short circuit in the fuel pressure (FP) sensor circuit power supply – possible
- Open ground circuit to the FP sensor – possible
- Faulty fuel pressure sensor – probable
- Failing powertrain control module (PCM) – unlikely
Diagnostic and Repair Procedures
- Check Technical Service Bulletins (TSBs)
First, consult TSBs specific to your vehicle. These bulletins may highlight known issues and manufacturer-recommended solutions, saving you time and money. - Locate and Inspect the FP Sensor
The fuel pressure sensor (FPS) is typically mounted on the fuel rail, near the injectors and intake manifold. Proceed as follows:- Visually inspect the connector and wiring for scratches, rubbing, exposed wires, burns, or signs of melted plastic.
- Disconnect the connector and check the metal terminals inside. If they appear burnt or have a greenish tint (corrosion), clean them with electrical contact cleaner and a plastic brush. Let dry, then apply electrical grease to the terminals.
- Clear Diagnostic Codes
If you have a scan tool, clear the stored codes and restart the vehicle. If code P2542 does not reappear, the issue was likely related to connections. - Test the FP Sensor and Related Circuits
Step 1: Check Power and Ground
- Turn off the engine and disconnect the FP sensor connector.
- Connect the black lead of a digital voltmeter to the ground terminal of the connector.
- Connect the red lead of the voltmeter to the power terminal.
- Turn the ignition on (engine off). Check manufacturer specifications: voltage should be 12V or 5V.
- If not, repair the power or ground wiring, or replace the PCM if necessary.
Step 2: Check Signal
- With the connector still disconnected, place the red voltmeter lead on the signal wire terminal.
- The voltmeter should read 5V.
- If no voltage is detected, repair the signal wiring or replace the PCM.
- Replace the FPS Sensor
If all previous checks are successful but code P2542 persists, the FPS sensor is likely faulty and will need replacement. However, do not rule out the possibility of a faulty PCM until the sensor has been replaced and tested. - Seek Professional Help
If you have doubts, entrust the diagnosis to a qualified automotive technician. Note that replacing a PCM requires vehicle-specific programming or calibration.