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.

Real-world scan data

Seen in

607

scans in the past year

Found in

0.1%

of scans

0.2%

of scans that found faults

Appears alongside · share of P0091 scans

P0113in 43.0% of scans

P0101in 31.8% of scans

P0380in 26.9% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P0091 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX