P2191: Mixture too lean at higher load (bank 1)
Under hard acceleration or uphill, bank 1 runs short of fuel. Often a weak fuel pump, a blocked filter or an air flow sensor reading low.
| Code | P2191 |
|---|---|
| System | Engine and transmission |
| Group | P21xx, Throttle, injection and emissions |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P2191 means
When the engine is working hard, the ECU adds as much fuel as it can on bank 1 and the mixture is still lean. Under high load the engine needs a lot of fuel, so the usual cause is fuel delivery or air measurement.
Most common causes
- Blocked fuel filter
- Weak fuel pump not delivering enough flow
- Dirty or faulty mass air flow sensor reading less air than is going in
- Dirty injectors not delivering enough fuel
- Intake leak after the air flow sensor (on turbo engines, a split hose)
- Faulty fuel pressure regulator
Symptoms
- Engine warning light on
- Lack of power at full throttle
- Surging or cutting out under load
- Misfires on hills or when overtaking
Can you drive with P2191?
With care You can drive without working the engine hard. Avoid full throttle and long climbs with a load until it is checked, as a lean mixture burns hotter.
How to check it
If your reader allows it, record fuel pressure (or fuel trims) and air flow live during a full throttle pull in a high gear. If pressure drops or trims shoot up, the fuel supply is the likely cause.
How to read and clear P2191 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P2191 with this same explanation and whether it’s confirmed, pending or permanent.
With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.
Similar codes
- P2179 Mixture too lean away from idle (bank 2)
- P2187 Mixture too lean at idle (bank 1)
- P2188 Mixture too rich at idle (bank 1)
- P2189 Mixture too lean at idle (bank 2)
- P2195 Oxygen sensor signal biased or stuck lean (bank 1, sensor 1)
- P2196 Oxygen sensor signal biased or stuck rich (bank 1, sensor 1)
- P2197 Oxygen sensor signal biased or stuck lean (bank 2, sensor 1)
- P2198 Oxygen sensor signal biased or stuck rich (bank 2, sensor 1)
- P2100 Throttle actuator A control motor circuit open
- P2101 Throttle actuator A control motor circuit range or performance
- P2102 Throttle actuator A control motor circuit low
- P2104 Throttle control system: forced idle
P2191 is a generic code, so it means the same on any make, for example on BMW, Citroën, Ford, Mercedes-Benz, Renault, Volvo. See what Final OBD does on your car in makes and models.
What does code P2191 mean?
When the engine is working hard, the ECU adds as much fuel as it can on bank 1 and the mixture is still lean. Under high load the engine needs a lot of fuel, so the usual cause is fuel delivery or air measurement.
Can you drive with P2191?
You can drive without working the engine hard. Avoid full throttle and long climbs with a load until it is checked, as a lean mixture burns hotter.
How do you clear P2191?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P2191 comes back.
Read it on your car
Final OBD reads the faults of every control unit for free, including each make’s own codes, and with Pro explains each one in plain English. Free clears engine faults at no cost.
Coming soon
Mid to late October 2026
If you want to try it in your car before anyone else, send us your email and we will add you as a tester.
info@finalobd.com