Fault code P2542 is called “Low Pressure Fuel System Sensor Circuit High” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P2542
OBD-II trouble code P2542 is defined as “low pressure fuel system sensor circuit high”. It is set when the PCM (Powertrain Control Module) detects an abnormal reading in the low pressure fuel system sensor circuit.
The fuel pressure sensor (FPS) converts the system fuel pressure into an electrical signal for the Powertrain Control Module (PCM). The PCM looks at the FPS sensor voltage to determine the exact amount of fuel to inject into the engine.
This code is set if the data received by the control module differs too much from the reference. It also checks the voltage signal from the FPS sensor to determine if it is correct when the engine is initially turned on by the key.
Code P2542 may be set due to mechanical (usually fuel pressure/volume) or electrical (fuel pressure sensor circuit) problems. The troubleshooting steps may vary depending on the manufacturer, sensor type, and wire color.
Symptoms of vehicle malfunctions
The main signal that an error P2542 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will illuminate (the code will be stored as a fault).
- There may also be other related trouble codes, such as ignition misfire.
- The engine stalls or fails to start.
- The engine cannot be accelerated, and throttle response is unresponsive.
- Reduced engine performance.
- Increased fuel consumption.
The severity of fault P2542 varies from moderate to high, the cause should be eliminated as soon as possible. As its occurrence can lead to serious mechanical damage later on.
Factors that can cause this error code
The error code P2542 can mean that one or more of the following problems have occurred:
- Faulty low pressure fuel system sensor.
- Corroded or damaged connector.
- Faulty or damaged wiring.
- Sometimes the cause is a faulty PCM module.
How to fix or reset OBD-2 code P2542
Some suggested steps for troubleshooting and fix the error code P2542:
- Read all stored data and error codes with an OBD-II scan tool.
- Clear the error codes from the computer memory.
- Test-drive the vehicle to find out if fault P2542 appears again.
- Check the quality of the fuel used.
- Visually inspect the wires and connectors going to the sensor.
- Test the low pressure fuel system sensor, and replace it if necessary.
Diagnose and repair of problems
The first step in the P2542 troubleshooting process, is to review the maintenance bulletins (TSB). In some cases, this can save a lot of time in the long run by pointing you in the right direction.
Next, you need to locate the FPS sensor for further inspection and testing. This sensor is usually located directly in the fuel line, next to the injectors and intake manifold.
Visually inspect the connector and wiring. Look for scratches, scuffs, exposed wires, burnt areas, or melted plastic. Disconnect the connector and carefully inspect the terminals inside the connector.
Check to see if they look burnt or have a green tint, indicating corrosion. If you need to clean the terminals, use an electrical contact cleaner and a plastic-bristle brush. Allow them to dry and apply electrical grease to the contact areas of the terminals.
If you have a scanner, clear the diagnostic trouble codes from the memory and see if the P2542 code comes back. If not, it’s likely that the problem was in the connections.
Check the sensor
If the P2542 code returns, you should check the FPS sensor and its associated circuits. With the key off, disconnect the electrical connector on the sensor. Connect the black wire of the digital voltmeter to the ground terminal on the sensor wiring harness connector.
Connect the red wire of the digital voltmeter to the power terminal on the transducer harness connector. Turn the ignition key and turn the engine off.
The voltmeter should read 12 or 5 volts, depending on the specifications of your vehicle. If it does not, repair a break in the wiring on the power or ground wire.
If the previous test passed, check the signal wire. With the connector disconnected, move the red voltmeter wire from the power wire terminal to the signal wire terminal. The voltmeter should read 5 volts. If it does not, repair a broken signal wire or replace the PCM.
If all previous checks are passed, but you keep getting fault P2542, it probably indicates a faulty FPS sensor. But a faulty PCM cannot be ruled out until the FPS sensor is replaced.
If you’re unsure, get help from a qualified automotive diagnostics technician. For proper installation of the PCM, it must be programmed or calibrated for the specific vehicle.
On which vehicles does this problem occur most frequently
Fault code P2542 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Audi
- Ford
- Land Rover (Evoque)
- Mercedes-Benz
- Volkswagen (Golf)
Fault code P2542 can sometimes be found with other errors. The most common are the following: P2539, P2540, P2541, P2543.
