What it means
The low-pressure fuel system sensor circuit signal is intermittent or erratic. The code does not identify the cause.
How it works
The low-pressure fuel sensor signal lets the control module monitor pressure and fuel delivery behavior. P2543 sets when that signal becomes intermittent or erratic, which can result from an unstable connector, wiring, sensor supply or ground, a failing sensor, or changing fuel pressure.
Common causes
Most likely first.
- Loose or corroded sensor connector
- Damaged or chafed wiring
- Faulty low pressure fuel sensor
- Poor sensor power or ground
- Unstable fuel pressure
Symptoms
- Check engine light
- Hesitation or stumble
- Reduced power
- Hard starting
How to diagnose it
- Check freeze-frame data and graph the low-pressure sensor reading on a scan tool to identify when it becomes erratic.
- Inspect the sensor connector and harness for corrosion, looseness, chafing, or damaged insulation.
- With live data displayed, gently move the harness and connector to check for signal dropouts, keeping clear of hot or moving parts.
- Test sensor power, ground, and signal continuity against the wiring diagram and manufacturer's specification.
- If the circuit remains stable, compare the sensor reading with an appropriate fuel-pressure test and assess the sensor for intermittent failure.
Common fixes
- Secure a loose sensor connector and repair corroded terminals.
- Repair or replace chafed or damaged sensor wiring.
- Restore a faulty sensor power or ground connection.
- Replace the low-pressure sensor if it drops out despite stable wiring and fuel pressure.
- Repair an unstable fuel-delivery problem if pressure testing confirms it.
Can I keep driving?
Limit driving if the engine stumbles, loses power, is hard to start, or may stall; avoid situations where an unexpected loss of power is dangerous. Intermittent fuel-pressure reporting or delivery can make the vehicle unpredictable.
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.