P219F Cylinder 4 is running at a noticeably different air-fuel ratio from the other cylinders, so the computer flags an imbalance on that cylinder

Air-fuel ratio imbalance, cylinder 4

P219F in short

P219F means cylinder 4 is running at a different air-fuel ratio from the other cylinders. A leaking or clogged injector, an air leak near that cylinder, or a misfire are typical causes, and several makers fixed false codes with software. Get it inspected soon; stop if the check engine light flashes.

Newer engines watch the oxygen sensor signal closely enough to tell when one cylinder's exhaust pulse is richer or leaner than the others. P219C to P219F name cylinders 1 to 4 individually; Nissan's bulletin defines P219F as air-fuel ratio imbalance in cylinder 4.

A real imbalance usually comes from that cylinder's injector delivering too much or too little fuel, or air getting in near it. Honda traced rough running on hybrids to a leaking injector that made the mixture rich and fouled the plugs.

Not every code is real: Nissan, Subaru and Hyundai fixed P219F with software on cars that drove normally.

Most likely causes

  1. Engine computer software (bulletin fix)

    Supported by vehicle data
    Why it ranks here
    Nissan, Subaru and Hyundai bulletins fix P219F with an ECM update, Nissan specifically when there is no drivability issue.
    What would change this
    Likelier on a covered model that drives normally.
    How to test the engine control module (ecm / pcm)

  2. Leaking or clogged fuel injector on cylinder 4

    Supported by vehicle data
    Why it ranks here
    Honda's bulletin links P219C-P219F to a leaking injector, and KBB lists injectors as a common imbalance cause.
    What would change this
    Likelier with rough running, fuel smell or a fouled cylinder 4 spark plug.
    How to test the fuel injector

  3. Air leak near cylinder 4 or in the boost path

    Supported by vehicle data
    Why it ranks here
    Ram traced P219F to a loose charge air cooler crimp, and KBB lists vacuum leaks.
    What would change this
    Likelier with a whistle, reduced boost or lean codes.
    How to test the vacuum hoses and intake leaks

  4. Fouled spark plug or misfire on cylinder 4

    Possible — needs testing
    Why it ranks here
    Honda found fouled plugs with these codes, though as a result of a rich mixture rather than the root cause.
    What would change this
    Likelier if P0304 or P0300 is stored too.
    How to test the spark plug

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes and freeze-frame data and check for bulletins covering your vehicle

    Low riskTool: OBD-II scan tool

  2. Pull the cylinder 4 spark plug and compare it with the others

    Use cautionTool: Spark plug socket

    Warning:Let the engine cool first; ignition coils carry high voltage, so keep the ignition off.

  3. Smoke-test the intake and boost system and have the injectors balance-tested

    Best left to a shopTool: Smoke machine, scan tool

    Warning:Fuel systems hold pressure with the engine off; follow the maker's procedure before opening any fuel line.

Symptoms

  • Check engine light
  • Often no change in how the car drives
  • Rough running or rattle
  • Whistle or reduced boost on turbo engines
  • Misfire or flashing check engine light Gets more serious: stop and have it checked.

Compare with: Rough idle with the check engine light on, Car shaking with the check engine light on

How to fix

  1. Ask a dealer to check your VIN for software or injector bulletins; Nissan, Subaru, Hyundai, Honda and Ram have published bulletins for P219F.

Parts and cost context

  • Fuel injector:Test before replacing; replace fouled plugs at the same time if an injector leaked. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Nissan

  • 2017–2018 · Pathfinder

    Supported by vehicle data

    ECM reprogram for P219F when there is no drivability issue. Also Infiniti QX60 (separate bulletin). Whether the bulletin is still current is not verified.

  • NTB18-026Status unverified

    MIL with P219F and no drivability issue; reprogram ECM

    2017–2018pathfinder · issued · NHTSA 10133205

    If the MIL is on with P219F (air-fuel ratio imbalance, cylinder 4) and there are no drivability issues, the ECM is reprogrammed.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Subaru

  • 2019–2020 · Crosstrek

    Supported by vehicle data

    ECM reprogram revising the air-fuel calculation for P219C-P219F. Whether the bulletin is still current is not verified.

  • 11-198-20Status unverified

    ECM reprogram for P219C-P219F

    2019–2020crosstrek · issued · NHTSA 10171918

    New ECM files revise the air-fuel calculation to address the check engine light with P219C, P219D, P219E or P219F.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Hyundai

  • 2018 · Sonata

    Supported by vehicle data

    ECM/TCM software for P219C-P219F on the 2.0T. Whether the bulletin is still current is not verified.

  • 5NP-R6Y5M-01Status unverified

    ECM/TCM software for P219C-P219F

    2018sonata · issued · NHTSA 10127004

    ECM and TCM software updates for 2018 Sonata 2.0T with a MIL from P219C-P219F cylinder imbalance codes or transmission ratio codes.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Honda

  • 2023–2025 · Accord

    Supported by vehicle data

    Leaking injector can cause rough running with P219C-P219F among the codes. Whether the bulletin is still current is not verified.

  • A25-044Status unverified

    Rough running from a possible injector leak; P219C-P219F may set

    2023–2025accord-hybrid, cr-v hybrid · issued · NHTSA 11020826

    Engine runs rough with a rattle and P0134/P0135; a possible fuel injector leak makes the mixture rich and fouls plugs. Other codes can include P0300, P219C-P219F and P0172.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ram

  • 2025 · 1500

    Supported by vehicle data

    Loose charge air cooler crimp with P219F, whistle and reduced boost. Whether the bulletin is still current is not verified.

  • 09-017-25Status unverified

    Loose charge air cooler crimp with imbalance codes

    20251500 · issued · NHTSA 11020753

    A loose charge air cooler case crimp can cause a whistle, reduced boost and P219C, P219D, P219F, P21A0 or P21A1.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0300Random or multiple-cylinder misfire detected

    Shares causes Supported by vehicle data

    Honda lists random misfire P0300 with P219C-P219F when an injector leaks.

  • P0172Engine computer has reached its limit removing fuel on bank 1: the mixture is rich

    Shares causes Supported by vehicle data

    Honda lists the rich code P0172 with P219C-P219F when an injector leaks.

  • P219AThe engine computer has detected that the cylinders on bank 1 are running at noticeably different air-fuel ratios from each other

    Same system Common general cause

    P219A is the bank-level imbalance code from the same monitor.

All Fuel trim (air-fuel mixture) codes

Sources and review

  1. Nissan NTB18-026: MIL with P219F air-fuel ratio imbalance cylinder 4 (Pathfinder) — Nissan North America / NHTSA ,
  2. Honda A25-044: engine runs rough with P0134/P0135, possible fuel injector leak (Accord Hybrid, CR-V Hybrid) — American Honda Motor / NHTSA ,
  3. p219a Code - Bank 1 Air-Fuel Ratio Imbalance — Kelley Blue Book (KBB Service Advisor)
  4. Final Regulation Order: 13 CCR §1968.2, Malfunction and Diagnostic System Requirements (OBD II) for 2004 and later passenger cars, light-duty trucks and medium-duty vehicles — California Air Resources Board
  5. 2026 Honda Pilot Owner's Manual: Indicator Coming On/Blinking (Malfunction Indicator Lamp) — American Honda Motor Co.
  6. Subaru 11-198-20: ECM reprogramming for P219C-P219F air-fuel ratio imbalance (Crosstrek) — Subaru of America / NHTSA ,
  7. Hyundai 5NP-R6Y5M-01: ECM/TCM software for P219C-P219F cylinder imbalance (Sonata 2.0T) — Hyundai Motor America / NHTSA ,
  8. FCA 09-017-25: loose charge air cooler case crimp, P219C/P219D/P219F (Ram 1500) — FCA US / NHTSA ,
Last reviewed
Written by
Saurabh K.
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