P0191 — Fuel Rail Pressure Sensor Circuit Range/Performance
Moderate severityWhat it means
P0191 is stored when the engine control unit sees a fault involving the fuel rail/system pressure. On direct-injection and diesel engines a high-pressure pump feeds the fuel rail, and a pressure sensor reports the result; the control unit needs this pressure to be accurate to fuel the engine correctly. A “range/performance” fault means the value is present but implausible — it does not agree with other sensors or expected conditions.
Common symptoms
- Readings that drift or disagree with related sensors
- Hard starting or long cranking
- Power loss, hesitation or limp mode
- Stalling under load in some cases
Likely causes
- Drifting, contaminated or aged sensor
- A mechanical issue skewing the reading
- A weak high-pressure pump or a clogged fuel filter
- A faulty pressure regulator or rail pressure sensor
What to check first
- Cross-check the reading against related sensors in live data on a cold start
- Compare commanded vs actual rail pressure in live data
- Inspect the pressure sensor connector and pump wiring
Can you keep driving?
Fuel-pressure faults can leave you stranded or drop the car into limp mode — diagnose before relying on it.
Frequently asked questions
What is the most common cause of P0191?
The most likely cause is: Drifting, contaminated or aged sensor. Several other faults can set P0191 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P0191 and keep driving?
Clearing P0191 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P0191?
P0191 is a moderate-severity code. The car is often still drivable, but have it diagnosed soon — the underlying problem can get worse and it may fail an emissions test.
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