Low Pressure Fuel Sensor Circuit Low

Symptoms

Symptoms of a P2541 engine code may include:

Malfunction indicator light illuminated
Vehicle unable to start
Longer than normal cranking times
Hesitation during acceleration
Decreased fuel economy

Potential Causes

The potential causes for this code being set are:

Short to ground in the signal circuit to the FP sensor
Short to ground in the power circuit of the FP sensor – possible
Faulty fuel pressure sensor – likely
Failed PCM – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check for Technical Service Bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix published by the manufacturer and can save you time and money when diagnosing.

Next, locate the FPS sensor on your specific vehicle. This sensor is typically directly screwed/mounted into the fuel rail, near the injectors and intake manifold. Once located, visually inspect the connector and wiring. Look for chafing, rubbing, bare wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they appear burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic-bristled brush if cleaning the terminals is necessary. Allow it to dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P2541 code returns. If it does not, the connections were likely your problem.

If the P2541 code returns, we will need to test the FPS sensor and its associated circuits. With the key off, disconnect the electrical connector from the FP sensor. Connect a black wire from the digital voltmeter to the ground terminal at the FP sensor wiring harness connector. Connect the red wire from the digital voltmeter to the power supply terminal at the FP sensor wiring harness connector. Turn the key to the engine off (run) position. Check the manufacturer’s specifications; the voltmeter should read 12 volts or 5 volts. If not, repair the power or ground wire wiring or replace the PCM.

If the previous test is successful, we will need to test the signal wire. With the connector still disconnected, move the red voltmeter wire from the power wire terminal to the signal wire terminal. The voltmeter should now read 5 volts. If not, repair the signal wire or replace the PCM.

If all previous tests are successful and you continue to get a P2541, this would most likely indicate a faulty FPS sensor, although a faulty PCM cannot be ruled out until the FPS sensor has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs must be programmed or calibrated to the vehicle to be installed correctly.

High Fuel Pump Low Pressure Circuit Sensor Circuit

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.

P2543 Intermittent Low Pressure Fuel Circuit Sensor Circuit

Symptoms

Symptoms of a P2543 engine code may include:

Malfunction indicator lamp illuminated
No start condition
Longer than normal cranking times
Hesitation during acceleration
Decreased fuel economy

Causes

Potential causes for this code definition include:

Open in signal circuit to FP sensor – possible
Short to voltage in signal circuit to FP sensor – possible
Short to ground in signal circuit to FP sensor – possible
Open in power or ground at FP sensor – possible
Faulty fuel pressure sensor – probable
Failed PCM – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the technical service bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix published by the manufacturer and can save you time and money when diagnosing.

Next, locate the FPS sensor on your specific vehicle. This sensor is typically directly screwed/mounted into the fuel rail, near the injectors and intake manifold. Once located, visually inspect the connector and wiring. Look for chafing, rubbing, bare wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they look burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P2543 code returns. If it does not, the connections were likely your problem.

If the P2543 code returns, ensure you have good fuel pressure by testing with a mechanical gauge. Check your vehicle manufacturer’s specifications. If fuel pressure and volume do not meet specifications, replace the fuel pump, clear the codes, and retest. If the P2543 is now gone, then the problem was mechanical.

If the P2543 code returns, we will need to test the FPS sensor and its associated circuits. With the key off, disconnect the electrical connector from the FP sensor. Connect a black wire from the digital voltmeter to the ground terminal at the FP sensor wiring harness connector. Connect the red wire from the digital voltmeter to the power supply terminal at the FP sensor wiring harness connector. Turn the key to the engine off position. Check the manufacturer’s specifications; the voltmeter should read 12 volts or 5 volts. If not, repair the open in the power or ground wiring or replace the PCM.

If the previous test passes, we will need to test the signal wire. With the connector still disconnected, move the red voltmeter wire from the power wire terminal to the signal wire terminal. The voltmeter should now read 5 volts. If not, repair the open in the signal wire or replace the PCM.

If all previous tests pass and you continue to get a P2543, this would most likely indicate a failing FPS sensor, although a faulty PCM cannot be ruled out until the FPS sensor has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs must be programmed or calibrated to the vehicle to be installed correctly.

P2544 – Torque Management Request “A” Input Signal

P2544 Possible Causes

Faulty Engine Control Module (ECM)
Faulty Transmission Control Module (TCM)
Engine Control Module (ECM) software update
Transmission Control Module (TCM) software update
Engine Control Module (ECM) harness is open or shorted
Poor electrical connection in Engine Control Module (ECM) circuit

How to Fix Code P2544

Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

Illuminated engine light (or service engine soon warning light)

P2544 Meaning

To improve shift feel, the Transmission Control Module (TCM) may request that the Engine Control Module (ECM) reduce engine torque during shift events. When such a request is received, the ECM responds by retarding base ignition timing and notifying the TCM that the request was successful. If the ECM is unable to comply with the request, the ECM sends the TCM a message indicating the request failed.
The torque reduction request is sent to the ECM via a communication network called CAN (Controller Area Network). Two circuits are used to communicate CAN data between the ECM and TCM.
A fault in the CAN will not cause the ECM to set diagnostic trouble codes (DTCs). If a CAN fault occurs, other DTCs will be set before this code.
The ECM sets the OBDII code when the TCM receives a torque reduction failure message from the ECM.

P2545 – Torque Management Request “A” Input Signal Range/Performance

P2545 Possible Causes

Faulty Engine Control Module (ECM)
Faulty Transmission Control Module (TCM)
Engine Control Module (ECM) software update
Transmission Control Module (TCM) software update
Engine Control Module (ECM) harness is open or shorted
Poor electrical connection in Engine Control Module (ECM) circuit

How to Fix Code P2545

Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

Illuminated engine light (or service engine soon warning light)

P2545 Meaning

The torque reduction request is sent to the ECM via a communication network called CAN (Controller Area Network). Two circuits are used to communicate CAN data between the ECM and TCM.
A fault in the CAN will not cause the ECM to set diagnostic trouble codes (DTCs). If a CAN fault occurs, other DTCs will be set before this code.
The ECM sets the OBDII code when the TCM receives a torque reduction failure message from the ECM.

P2546 – Low Torque Management Request “A” Input Signal

P2546 Possible Causes

Faulty Engine Control Module (ECM)
Faulty Transmission Control Module (TCM)
Engine Control Module (ECM) software update
Transmission Control Module (TCM) software update
Engine Control Module (ECM) harness is open or shorted
Poor electrical connection in Engine Control Module (ECM) circuit

How to Fix Code P2546

Symptoms

Possible

Engine light on (or Service Engine Soon warning light)

P2546 Meaning

To improve shift feel, the Transmission Control Module (TCM) may request that the Engine Control Module (ECM) reduce engine torque during shift events. When such a request is received, the ECM responds by retarding base ignition timing and notifying the TCM that the request was successful. If the ECM is unable to comply with the request, the ECM sends a message to the TCM indicating that the request failed.
The torque reduction request is sent to the ECM via a communication network called CAN (Controller Area Network). Two circuits are used to communicate CAN data between the ECM and TCM.
A fault in the CAN will not cause the ECM to set diagnostic trouble codes (DTCs). If a CAN fault occurs, other DTCs will be set before this code.
The ECM sets the OBDII code when the TCM receives a torque reduction failure message from the ECM.

P2547 – High Torque Management Request “A” Input Signal

P2547 Possible Causes

Faulty Engine Control Module (ECM)
Faulty Transmission Control Module (TCM)
Engine Control Module (ECM) software update
Transmission Control Module (TCM) software update
Engine Control Module (ECM) harness is open or shorted
Poor electrical connection in Engine Control Module (ECM) circuit

How to Fix Code P2547

Possible Symptoms

Illuminated engine light (or service engine soon warning light)

P2547 Meaning

P2548 – Torque Management Request “B” Input Signal

P2548 Possible Causes

Faulty Engine Control Module (ECM)
Faulty Transmission Control Module (TCM)
Engine Control Module (ECM) software update
Transmission Control Module (TCM) software update
Engine Control Module (ECM) harness is open or shorted
Poor electrical connection in Engine Control Module (ECM) circuit

How to Fix Code P2548

Possible Symptoms

Illuminated engine light (or service engine soon warning light)

P2548 Meaning

P2549 – Torque Management Request “B” Input Signal Range/Performance

P2549 Possible Causes

Faulty Engine Control Module (ECM)
Faulty Transmission Control Module (TCM)
Engine Control Module (ECM) software update
Transmission Control Module (TCM) software update
Engine Control Module (ECM) harness is open or shorted
Poor electrical connection in Engine Control Module (ECM) circuit

How to Fix Code P2549

Possible Symptoms

Illuminated engine light (or service engine soon warning light)

P2549 Meaning

To improve shift feel, the Transmission Control Module (TCM) may request that the Engine Control Module (ECM) reduce engine torque during shift events. When such a request is received, the ECM responds by retarding base ignition timing and notifying the TCM that the request was successful. If the ECM is unable to comply with the request, the ECM sends the TCM a message indicating that the request failed.
The torque reduction request is sent to the ECM via a communication network called CAN (Controller Area Network). Two circuits are used to communicate CAN data between the ECM and TCM.
A fault in the CAN will not cause the ECM to set diagnostic trouble codes (DTC). If a CAN fault occurs, other DTCs will be set before this code.
The ECM sets the OBDII code when the TCM receives a torque reduction failure message from the ECM.

P254A -PTO- Speed Select Sensor / Switch 1 Circuit / Open

How severe is this DTC?

The severity of this code is generally not severe as it will likely only affect PTO functions but not the vehicle’s normal functions.

What are some symptoms of the code?

Symptoms of a P254A fault code may include:

Power take-off auxiliary equipment will not operate
Check engine light illuminated

What are some common causes of the code?

Causes

of this P254A code may include:

Faulty PTO sensor
Open or short circuit in power take-off detection circuit
Defective or damaged wiring
Corroded, damaged, or loose connector
Faulty fuse or fusible link (if applicable)
Faulty PCM

What are the troubleshooting steps for P254A?

The first step in the troubleshooting process for any malfunction is to search for Technical Service Bulletins (TSBs) for the specific vehicle by year, model, and engine/transmission configuration. In some circumstances, this can save significant time in the long run by pointing you in the right direction.

The second step is to locate all components associated with the power take-off circuit and look for obvious physical damage. Perform a thorough visual inspection to check associated wiring for obvious defects such as scraping, rubbing, bare wires, or burns. Then check connectors and connections for security, corrosion, and damaged pins. This process should include all wiring connectors and connections to all components, including the PCM. Consult vehicle-specific technical data to verify the oil level safety circuit configuration and see if a fuse or fusible link is incorporated in the circuit.

Advanced Steps

Advanced steps become very vehicle-specific and require appropriate advanced equipment to function accurately. These procedures require a digital multimeter and vehicle-specific technical references. In this situation, an oil pressure gauge may facilitate the troubleshooting process.

This article is strictly informational and technical data and service bulletins specific to your vehicle should always take priority.