OBD-II Code · Fuel & Air
P2191
System Too Lean at High Load (Bank 1)
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$80–$700
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Bank 1 lean under heavy throttle.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Hesitation under load
Likely causes
- Weak fuel pumpMost common
- Clogged filter
- Leaking intake
Read the full diagnostic procedureP2191 is the bank 2 mirror of P2190 — bank 2 runs RICH at idle specifically, STFT + LTFT pinned at -10% to -25% at warm idle and trims cleaning back…
P2191 is the bank 2 mirror of P2190 — bank 2 runs RICH at idle specifically, STFT + LTFT pinned at -10% to -25% at warm idle and trims cleaning back up at cruise.
Bank-specific plus idle-only narrows the diagnostic the same way P2189 does for lean
causes that affect both banks globally (dirty MAF, failed global FPR, saturated EVAP canister venting into a common plenum) tend to throw P2190 AND P2191 simultaneously, so a solo P2191 points at a fault mechanically isolated to bank 2 — a single leaking bank-2 injector, a bank-2-side purge or PCV path stuck open, a bank-2 fuel-pressure imbalance from a clogged crossover, or coked bank-2 intake valves on direct-injection setups. Cheapest-first: pull the bank-2 plugs and compare against bank-1 (sooty bank 2 + clean bank 1 = diagnostic photo). Scope bank-2 injectors looking for a slow-closer. Check fuel rail balance on dual-rail engines — some V6/V8 designs (Ford 3.5L EcoBoost, GM LT1/LT4) run separate rails per bank and a clogged crossover or failed pressure sensor on one rail throws the other side rich. The at-idle code is the giveaway — leaky bank-2 injector or coked bank-2 intake valves for rich; don't condemn the O2 sensor.
Vehicle-specific patterns2011-2017 Ford 3.5L EcoBoost (F-150, Flex, Taurus SHO, Explorer Sport) throws P2191 from a sticking high-pressure fuel pump cam-follower on the bank-…
- 2011-2017Ford 3.5L EcoBoost (F-150, Flex, Taurus SHO, Explorer Sport) throws P2191 from a sticking high-pressure fuel pump cam-follower on the bank-2 side and from carbon-coked bank-2 intake valves around 80k-120k miles (no port-injection wash on direct-injection).
- 2007-2014GM 5.3L AFM trucks throw P2191 from collapsed AFM lifters dumping crankcase oil into the bank-2 PCV path.
- 2005-2012Nissan Pathfinder / Frontier / Xterra VQ40DE 4.0L V6 throws P2191 from a leaking bank-2 injector and from a stuck-open canister purge solenoid that vents to the bank-2 intake.
- 2008-2014Cadillac CTS / SRX / STS 3.6L LFX V6 throws P2191 from carbon buildup specifically on the bank-2 intake valves — walnut-blast cleaning around 100k miles is the GM-recommended service.
Estimated repair$60 to $1,400.
Look up another code
P2191 — frequently asked
What does a P2191 code mean?
Bank 1 lean under heavy throttle.
What causes a P2191 code?
Common causes: Weak fuel pump; Clogged filter; Leaking intake.
What are the symptoms of a P2191 code?
Typical symptoms: Check engine light; Hesitation under load.
Is it safe to drive with a P2191 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $80-$700.
How do I diagnose a P2191 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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