P0191: Fuel Rail Pressure Sensor "A" Circuit Range/Performance
P0191 means Fuel Rail Pressure Sensor "A" Circuit Range/Performance. The fuel rail pressure sensor reports fuel pressure to the engine computer. The signal is inside its electrical limits, but it does not make sense compared with what the module expects from other sensors or from engine conditions (a "range/performance" fault). The part is often working electrically but reporting a wrong or implausible value.
Can I keep driving? Drivable with care. Diagnose soon: performance, economy or other components can be affected.
Common symptoms
- Check engine light on
- Hesitation or loss of power
- Hard starting
- Possible limp mode
Possible causes
- Failed fuel rail pressure sensor
- Damaged connector or wiring
- 5 V reference circuit fault
- Actual fuel pressure problem (range/performance codes)
How to diagnose P0191
- Compare the sensor reading with a mechanical fuel pressure gauge where possible.
- Check the connector, 5 V reference, ground and signal.
- Look for other sensor codes on the same 5 V reference.
What the code means, digit by digit
Generic codes have the same definition on every OBD-II vehicle (petrol cars from model year 1996 in the US, 2001 in the EU; diesels later). Manufacturers can add their own enhanced codes; those are not listed here.
Related codes
General guidance only. Fault codes describe what the engine computer saw, not which part failed: confirm with testing before replacing parts, and follow the vehicle's service information.