What it means
The low-pressure fuel system sensor circuit signal is above the expected limit. The code does not establish a particular control strategy or cause.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The low-pressure fuel system sensor sends a pressure signal to the control module. P2542 sets when the signal rises above its expected limit; a high reading can result from a signal short to reference voltage, an open signal return, or resistance at corroded connector pins, and does not by itself confirm high fuel pressure.
Common causes
Most likely first.
- Signal wire shorted to reference voltage
- Open signal return
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine warning light
- Hard starting or extended cranking
- Hesitation, reduced power, or stalling
How to diagnose it
- Review freeze-frame data and live low-pressure fuel readings to determine whether the high signal is constant or appears only under particular conditions.
- Inspect the sensor connector for corrosion or damaged pins, and check the harness for a signal wire contacting the reference-voltage circuit.
- Use the wiring diagram to test the signal return for an open circuit and check sensor power, ground, and signal against the manufacturer's specification.
- Compare the scan-tool pressure value with an appropriate independent pressure test to determine whether actual fuel pressure is also high.
- If wiring and actual pressure are normal, test the low-pressure sensor and module input using the vehicle's service procedure.
Common fixes
- Repair a signal wire shorted to reference voltage.
- Restore an open signal return or repair its connection.
- Clean or replace corroded connector terminals.
- Replace the sensor if its output remains high with correct wiring and actual pressure.
Can I keep driving?
Limit driving if the engine is hard to start, hesitates, loses power, or stalls, and avoid routes where a stall would be hazardous. The high signal may be electrical rather than evidence of high pressure, but unreliable fuel-pressure information can affect engine operation.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.