P2191

System Too Lean at Higher Load Bank 1

Fuel & air metering Generic OBD-II Medium

What it means

P2191 means bank 1 runs too lean specifically at higher engine loads — the fuel system can't supply enough fuel when demand climbs. Because the fault appears under load rather than at idle, it often points to a fuel-delivery limit (pressure, pump, filter, or injectors) or an under-reading MAF, though vacuum leaks can contribute too. It won't stop the engine from starting but should be addressed to prevent misfire and converter damage.

Medium

Can I keep driving? Driveable at light throttle, but under load the engine can hesitate, stumble, or misfire from running lean; fix soon to avoid converter and engine damage.

Real-world scan data

Seen in

346

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P2191 scans

P0300in 23.7% of scans

P2187in 17.6% of scans

P0303in 16.2% 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
Hesitation or stumble under acceleration and load
Reduced power at higher engine loads
Surging or lean misfire when pushed
May enter a reduced-power/failsafe mode

Common causes

Most likely first

Low fuel pressure or restricted fuel delivery that can't keep up under loadLikely
Faulty or contaminated MAF sensor under-reading airflowCommon
Intake or vacuum leak on bank 1Common
Weak, dirty, or restricted fuel injectors on bank 1Less often
Clogged fuel filter or weak fuel pumpLess often
Faulty upstream (front) O2 sensor or an exhaust leak near it skewing readingsLess often

How to diagnose & fix

Work through it in order

Read freeze-frame and fuel-trim data, paying attention to trims at higher load/RPM.
Check fuel pressure and volume under load — a pump or filter that can't keep up is a common higher-load cause.
Inspect and clean the MAF sensor and check for intake/vacuum leaks on bank 1.
Test injector flow and inspect for exhaust leaks near the front O2 sensor; replace parts only once data confirms them.

FAQ

Quick answers

Is it safe to drive with P2191?+

Light driving is usually fine, but hard acceleration runs the engine lean and can misfire and overheat the converter, so avoid heavy loads until it's repaired.

Can I just clear P2191?+

It comes back once trims go lean under load again. The fuel-delivery, airflow, or leak problem behind it has to be fixed first.

Read & clear P2191 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