Ask CarFix

P219C: Cylinder 1 Air-Fuel Ratio Imbalance

Severity: high

What it means: The engine computer sees that cylinder 1 is running richer or leaner than the other cylinders, based on oxygen sensor and crank/cam sensor data.

Safe to drive? Get it checked soon. It often comes with rough running or reduced power. If the engine is misfiring badly or the check-engine light is flashing, don't drive it.

Common symptoms

Likely causes, ranked

  1. Faulty or clogged fuel injector on cylinder 1Shop
  2. Ignition problem (spark plug or coil) on cylinder 1DIY or shop
  3. Intake or vacuum leak near cylinder 1Shop
  4. Low compression or other mechanical problemShop
  5. Oxygen sensor or wiring faultShop
Advertisement

Vehicle-specific notes

  • :

Answers that mention P219C

DIY or shop?

Swapping a coil or plug to test can be DIY. Injector, fuel system and compression testing are usually shop work.

Vehicle notes

  • Kia Carnival 3.5 V6: Kia has a bulletin for reduced power with cylinder air-fuel imbalance codes in the P219C to P21A1 range, involving high-pressure injectors and fuel piping. See the related Carnival answer.

Sources

Safety / mechanic note

Running a misfiring engine can damage the catalytic converter, and a fuel leak is a fire risk. Verify with a mechanic.

Advertisement

Sources