Powertrain, generic (extended)

P219F Cylinder 4 Air-Fuel Ratio Imbalance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P219F singles out cylinder 4, the last cylinder on four-cylinder engines. Infiniti issued a bulletin for 2017 to 2018 QX60 with the direct-injection VQ35DD that stored only P219F without any driveability complaint; the remedy was ECM reprogramming followed by the idle air volume learn. Honda found the opposite case on 2023 to 2025 CR-V Hybrid and Accord Hybrid: a leaking injector made the mixture rich, fouled spark plugs and caused rattling and rough running, with P219C to P219F, P0172 and A/F sensor heater codes; all injectors and the fouled plugs were replaced and Honda warned against changing the A/F sensor first. Hyundai's 2018 Sonata 2.0 turbo also set P219F through software. Reading the spark plug of the flagged cylinder is a quick first check for rich or lean burning.

Likely causes

Leaking injector at cylinder 4
Oversensitive detection fixed by ECM reprogramming (e.g. Infiniti QX60, Hyundai Sonata)
Fouled spark plug as a consequence of a rich cylinder

Symptoms

  • Check engine light on
  • Rough running or rattling noise when an injector leaks
  • No symptom when the cause is software

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–1,500
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injector

Related codes

P219AP219EP21A0P0304P0172

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.