P0191: Fuel rail pressure sensor range or performance problem
The pressure reported by the rail sensor does not match what the ECU expects. It may be the sensor, but it can also be a genuine pressure problem.
| Code | P0191 |
|---|---|
| System | Engine and transmission |
| Group | P01xx, Air and fuel metering |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0191 means
The ECU compares the rail pressure it reads with the pressure it has asked for and with how it reacts when you accelerate. If they do not match, it stores this code. Unlike an electrical fault, the cause can be either a sensor that reads wrongly or a real pressure problem in the fuel system.
Most common causes
- Blocked fuel filter
- Drifting fuel rail pressure sensor or a poor connector
- High pressure pump or in-tank pump not delivering enough pressure
- Sticking pressure regulator or pressure control valve
- Injector with excessive return flow or an internal leak
- Very low fuel level or air in the system
Symptoms
- Engine warning light on
- Lack of power, especially under hard acceleration
- Long cranking or hard starting
- Hesitation or stalling
Can you drive with P0191?
With care You can drive with care, but the car may go into limp mode or cut out. Get it checked soon, especially if it is hard to start.
Open the bonnetthe in-depth explanation
How to check it
On the reader, compare desired and actual rail pressure live, at idle and while accelerating. If the actual value falls behind when you ask for power, suspect the filter or pump; if they match but the code still sets, the sensor is more likely.
How to read and clear P0191 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0191 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P018D The fuel pressure sensor B gives a higher signal than normal
- P018E The fuel pressure sensor B fails now and then
- P018F The fuel pressure relief system activates too frequently
- P0190 Fuel rail pressure sensor circuit malfunction
- P0192 Fuel rail pressure sensor circuit low
- P0193 Fuel rail pressure sensor circuit high
- P0194 The fuel rail pressure sensor (bank 1) fails now and then
- P0195 The engine oil temperature sensor is not working properly
- P0100 Mass or volume air flow sensor circuit fault
- P0101 Air flow sensor range or performance problem
- P0102 Air flow sensor circuit low input
- P0103 Air flow sensor circuit high input
To understand it properly
We explain how that system works, with drawings and no waffle, in our mechanics guide: Fuel.
What does code P0191 mean?
The ECU compares the rail pressure it reads with the pressure it has asked for and with how it reacts when you accelerate. If they do not match, it stores this code. Unlike an electrical fault, the cause can be either a sensor that reads wrongly or a real pressure problem in the fuel system.
Can you drive with P0191?
You can drive with care, but the car may go into limp mode or cut out. Get it checked soon, especially if it is hard to start.
How do you clear P0191?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0191 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
