Fuel Rail Pressure Sensor A Circuit
On common rail engines (diesel and direct-injection petrol), this sensor measures the fuel pressure in the rail; the ECU uses it to control the injection.
What the car has detected
The rail pressure sensor signal is missing or impossible: a broken or shorted wire, a damaged connector or a faulty sensor.
The engine may go into limp mode, lack power, stall or not start. Have it checked soon and avoid long trips in the meantime.
Symptoms
- Engine warning light on
- Loss of power or limp mode
- Longer or harder starting
- The engine stalls or will not start
Possible causes
- Damaged sensor wiring or connector
- Short to ground near the sensor
- Faulty rail pressure sensor
- Engine computer fault (rare)
Checks for the garage
- Check the rail pressure sensor connector and wiring
- Measure the sensor's supply (usually 5 V) and earth
- Check with the diagnostic tool that the rail pressure makes sense when cranking and at idle
Next step
Ask them to check the rail pressure sensor, its connector and wiring, and the supply it gets from the ECU.
Go to a garage soon. If the car stalls or will not start, do not force it: call roadside assistance.