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.
Open the bonnetthe in-depth explanation
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 its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
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 an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P218D The throttle or fuel inhibit circuit B signal is low
- P218E The throttle or fuel inhibit circuit B signal is high
- P218F The engine warning lamp is illuminated
- P2190 The fuel and air mixture is too rich at idle on bank 2
- P2192 The mixture on bank 1 is too rich when the engine is under high load
- P2193 The mixture on bank 2 is too lean when the engine is under high load
- P2194 The mixture on bank 2 is too rich when the engine is under high load
- P2195 Oxygen sensor signal biased or stuck lean (bank 1, 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
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 and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
