P219A⛽ Fuel / air metering (cylinder-to-cylinder balance)Stop and fix promptly

P219A: Bank 1 Air/Fuel Ratio Imbalance (Meaning, Causes, Fixes)

Reviewed 2026-10-22 · Based on 3 cited source(s)

What P219A means

The powertrain control module (PCM) uses the upstream oxygen sensor, sometimes called an air-fuel ratio sensor, to watch the exhaust from each bank of the engine. Bank 1 is the side with cylinder 1; on a 4-cylinder engine there is only one bank. OBD-Codes.com describes P219A as the PCM detecting an air-to-fuel ratio imbalance for Bank 1. Manufacturer service information is more specific: GM's description calls it a cylinder-to-cylinder rich or lean imbalance, found by analyzing the upstream oxygen sensor signal, and Mitsubishi's 2023 service manual says it sets when the air-fuel ratio is uneven between cylinders because of a difference in combustion between them. In other words, the bank as a whole may average out fine while one cylinder runs off. The companion code for Bank 2 is P219B.

Severity: can I keep driving?

Stop and fix promptly

Get it fixed soon. OBD-Codes.com says P219A should be treated as severe and fixed as quickly as possible, since a cylinder running too rich or too lean hurts performance and fuel economy and often comes with misfire codes. If the engine misfires badly, shakes, loses power, or the check engine light flashes, keep driving to a minimum, because misfires can overheat and damage the catalytic converter.

Common symptoms

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

  1. A fuel injector on one cylinder flowing more or less than the others; GM says a difference as small as 5% can set P219A on some engines (GM PIP5301A, Mitsubishi service manual)
  2. Ignition problems such as a weak spark plug or coil (Mitsubishi service manual)
  3. Low compression or carbon deposits around the intake and exhaust valves (Mitsubishi service manual)
  4. A failed upstream air-fuel ratio / oxygen sensor or damaged sensor wiring (Mitsubishi service manual, OBD-Codes.com)
  5. A large engine vacuum leak or an exhaust leak (OBD-Codes.com)
  6. A faulty mass air flow (MAF) or manifold pressure (MAP) sensor (OBD-Codes.com)
  7. A weak fuel pump or clogged fuel filter (OBD-Codes.com)
  8. A faulty engine computer, which is rare (Mitsubishi service manual)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

  1. Read all stored codes and fix misfire, MAF, MAP and throttle position codes first. Both OBD-Codes.com and Mitsubishi say to deal with other codes before P219A.
  2. If a misfire code points to one cylinder (for example P0302), start there. GM says misfire counts can point to the cylinder causing the imbalance.
  3. Check the spark plugs and ignition coils, especially on the cylinder that shows misfires.
  4. Listen and look for vacuum leaks around the intake manifold and hoses, and for exhaust leaks near the exhaust manifold.
  5. Inspect the upstream oxygen sensor wiring and connector for burned, chafed or loose wires (OBD-Codes.com).
  6. Write down the freeze frame data, clear the code and drive normally. OBD-Codes.com notes that if it does not return quickly it may be intermittent and harder to diagnose.

Typical fixes

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

  • The engine misfires, runs rough, or the check engine light flashes
  • Plugs, coils and obvious leaks check out but the code keeps coming back
  • Testing needs a fuel injector balance or flow test, a compression test, or live sensor data, which GM and Mitsubishi both call for
  • Your vehicle may have a technical service bulletin for P219A; GM issued one (PIP5301A) for 2010-2015 2.4L Equinox, Terrain, Captiva and Verano

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P219A serious?

OBD-Codes.com says it should be treated as severe and fixed as quickly as possible. A cylinder running out of balance wastes fuel, can cause misfires, and misfires can damage the catalytic converter.

Does P219A mean I need an oxygen sensor?

Not necessarily. The oxygen sensor is how the computer detects the imbalance, and a failed sensor is one possible cause, but GM and Mitsubishi service information point first to problems at a single cylinder such as a fuel injector, ignition parts, compression or leaks.

Why do sources describe P219A differently?

OBD-Codes.com describes it as a bank-wide air-fuel imbalance and lists bank-wide causes like a large vacuum leak, a weak fuel pump or a bad MAF sensor. GM and Mitsubishi describe a cylinder-to-cylinder imbalance and list causes at one cylinder. Both kinds of causes are worth checking, starting with any misfire codes.

How much does it cost to fix P219A?

None of the sources give a repair cost. It can range from a spark plug or coil to a fuel injector, an oxygen sensor, or engine repair, so get a diagnosis or written estimate first.

Sources

  1. OBD-Codes.com: P219A Bank 1 Air/Fuel Ratio Imbalance (rated severe)
  2. Mitsubishi 2023 service manual: DTC P219A-00 Air-fuel ratio cylinder imbalance
  3. GM bulletin PIP5301A: Diagnostic Tips for DTC P219A (via NHTSA)

Last reviewed 2026-10-22. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.