P0191 Code: Fuel Rail Pressure Sensor Range — Causes & Fix
P0191 means the fuel rail pressure sensor is reading out of its expected range — critical on direct-injection and diesel high-pressure fuel systems.
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $80 – $900
- Time to fix
- 30 minutes – 2 hours
What it means
Causes include a failed rail pressure sensor, a genuine fuel-pressure problem, or wiring faults. P0191 is a generic OBD-II code defined in the SAE J2012 standard, so it applies to virtually any 1996-or-newer OBD-II vehicle regardless of make. Fix the underlying fault, then clear the code with an OBD-II scan tool — it will return if the problem isn't resolved.
Symptoms
- Check engine light on
- Hard starting, power loss, or stalling
- Rough running
How to fix it
- 1
Verify actual rail pressure
1. Compare the sensor reading to commanded pressure on a scan tool. 2. Rule out a real fuel-supply problem.
- 2
Replace the sensor
1. Replace a faulty rail pressure sensor, then clear the code.
Frequently asked questions
Can P0191 cause a no-start?
Yes — on high-pressure DI/diesel systems a bad rail-pressure signal can prevent proper fuelling. Verify actual pressure before replacing parts.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.