P0091
Fuel Pressure Regulator A Control Circuit Low
Fuel & air metering
Generic OBD-II
High
What it means
P0091 means the ECM detected a low-voltage (short-to-ground or open) condition in the control circuit for fuel pressure regulator "A". The ECM uses this regulator to set fuel-rail pressure, so a circuit fault can leave pressure wrong — causing hard starting, stalling, or a no-start, often with limp mode. The usual causes are the regulator solenoid, its connector, or wiring.
High
Can I keep driving? Often no — a regulator circuit fault can drop fuel-rail pressure, causing hard starting, stalling, a no-start, or limp mode. Fix before relying on the car.
Common symptoms
What you'll notice
- Check-engine light on
- Hard starting or no-start
- Stalling, especially under load
- Reduced power or limp mode
Common causes
Most likely first
- Short-to-ground or open (low-voltage fault) in the fuel pressure regulator control circuitLikely
- Failed fuel pressure regulator / control solenoidCommon
- Corroded or loose connector at the regulatorCommon
- Damaged wiring in the control circuitLess often
- ECM control-circuit driver faultLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check commanded vs actual fuel-rail pressure on a scan tool.
- Inspect the regulator connector and control wiring for a short-to-ground or open.
- Measure the regulator solenoid resistance against spec.
- Verify power and ground at the regulator connector.
- Replace the fuel pressure regulator if faulty; suspect the ECM only after wiring is verified good.
FAQ
Quick answers
Is it safe to drive with P0091?+
Not reliably. Low or unstable fuel pressure can cause stalling or a no-start, so treat it as a fix-now item.
Can I just clear P0091?+
It returns until the control circuit or the regulator is repaired, and the starting/stalling risk remains.
Related codes
Often seen with P0091
Read & clear P0091 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX