P0193Powertrain
Powertrain · SAE
Fuel Rail Pressure Sensor Circuit High
Meaning
The fuel pressure sensor on the common rail outputs a voltage above the maximum operating range. The ECM interprets the signal as a short to the reference voltage or an internal sensor failure.
Common causes
- Short of the signal wire to supply voltage (5 V or battery)
- Failed rail pressure sensor (drifting high)
- Open sensor ground wire
- Damaged connector with accidental bridging
- Electrical interference on the signal wire
Symptoms
- Check-engine light on
- Rail pressure reading at full scale even with engine off
- Injector flow reduction for protection (limp-home)
- Power loss and smoke
- Possible pressure relief valve activation
Severity
High: the ECM may over-reduce rail pressure for protection, causing severe power loss or shutdown.
What to do
- Measure signal voltage at the connector: near 5 V suggests short to supply or open ground
- Verify sensor ground continuity
- Inspect wiring for bridging or damage
- Replace the rail pressure sensor if the circuit is intact
- Check actual rail pressure with an external gauge