What does P0191 mean?
The fuel rail pressure sensor reads fuel pressure in the rail that feeds the injectors. On diesels and direct-injection gas engines, pressure can run from a few thousand psi to well over 25,000 psi, and the computer controls it closely.
The circuit is electrically intact, but the reading does not make sense for the operating conditions. Sometimes the sensor is fine and is reporting a real problem.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Check engine light
- Hard starting or no start
- Loss of power
- Stalling
Common causes
- Sensor reading that does not match other sensors (a skewed or slow sensor)
- Mechanical problem the sensor is correctly reporting
- Restricted or leaking hose/port to the sensor
- High resistance in the connector
- Failed rail pressure sensor
- Wiring or connector problems
- Actual fuel pressure problem (pump, regulator, filter)
How to diagnose P0191
- Compare the live reading with related sensors and with known values (key on, engine off and at idle).
- Inspect hoses, ports and the connector for damage, oil or corrosion.
- Only replace the sensor after ruling out the real-world condition it measures.
- Compare commanded and actual rail pressure in live data.
- Check reference, ground and signal at the sensor.
How to fix it
- Repair wiring
- Replace the rail pressure sensor (on some engines it is part of the rail)
Estimated repair cost
Likely repairs for P0191 run from about $100 to $450, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Fuel rail pressure sensor | $150 - $450 |
| Wiring/connector repair | $100 - $400 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0191?
High severity
Can cause stalling or no-start, so fix it before relying on the vehicle.
P0191 FAQ
What does P0191 mean?
P0191 stands for "Fuel Rail Pressure Sensor "A" Circuit Range/Performance". The fuel rail pressure sensor reads fuel pressure in the rail that feeds the injectors.
Can I drive with a P0191 code?
Can cause stalling or no-start, so fix it before relying on the vehicle.
How much does it cost to fix P0191?
It depends on the cause. The likely repairs for P0191 range from about $100 to $450 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0191?
The most common causes are: sensor reading that does not match other sensors (a skewed or slow sensor); mechanical problem the sensor is correctly reporting; restricted or leaking hose/port to the sensor.