Fuel Rail/System Pressure - Too High
On direct injection engines (common rail diesels and many petrol engines), fuel reaches the injectors at very high pressure from a shared pipe, the rail. A sensor measures that pressure and a regulator adjusts it. This code means rail pressure has gone above the maximum allowed.
What the car has detected
The engine computer has measured a rail fuel pressure above the maximum allowed deviation over the requested value.
You can drive carefully, but have it checked soon: if the pressure really is high, the engine may knock and smoke. Often the cause is the sensor or its wiring.
Symptoms
- Engine warning light on
- Engine sounds harsher (combustion knock)
- Smoke from the exhaust
- Loss of power or limp mode
Possible causes
- Faulty rail pressure sensor or a wiring or connector fault
- Sticking pressure regulator or valve
- Voltage drops from the battery or the engine computer's supply
- On some engines, a stretched timing chain that throws the pump out of time
Checks for the garage
- Read the other codes (for example pump timing ones) and the freeze frame data
- Compare actual and requested rail pressure in live data, at idle and when accelerating
- Command the pressure up and down with diagnostics and see whether the sensor follows
- Check power, earth and wiring of the regulator and the pressure sensor
- Check battery and charging voltage
Next step
Have the rail pressure sensor, its wiring and the pressure regulator checked.
Go to a garage if the code comes back or if you notice knocking or smoke. Checking the sensor and regulator needs diagnostics.