P219A: Bank 1 Air-Fuel Ratio Imbalance
The fuel-trim values across cylinders on bank 1 differ enough that the bank-average air-fuel ratio is biased — a single cylinder is significantly leaner or richer than the rest. Detected by short-term-fuel-trim variance or by the wide-band O2 sensor harmonic monitor.
What P219A means
P219A is a generic OBD-II powertrain code in the fuel & air group. Bank 1 is the side of the engine with cylinder 1 (inline engines only have bank 1).
- Check engine light
- Usually on
- Emissions-related
- Yes — can fail inspection
- Limp mode possible
- Not typical
- Drive cycle to clear
- Not required
Get it fixed
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Common causes
- 01One injector clogged or leakingMost likely
- 02Vacuum leak at one intake runnerPossible
- 03Low compression on one cylinderLess likely
Can I drive with P219A?
Usually yes, for a short time.
The car will often drive normally, but get it diagnosed soon. Left alone it can raise fuel use and emissions and will fail an OBD inspection. If you notice rough running, warning lights flashing, overheating or a burning smell, stop driving.
Why we rate it moderate
- Turns on the check engine light
- Emissions-related: will usually fail an OBD inspection
Severity is our rule-based rating from the code’s flags in OBDex and the system it affects, not an inspection of your car. If the check engine light is flashing, or you notice overheating, low oil pressure, or brake or steering problems, stop driving and get help.
How to diagnose P219A
- 1
Confirm the code and save freeze-frame data
Read the codes with an OBD-II scan tool and note every code, not just P219A. Save the freeze-frame data (speed, load, temperature when the fault set) before clearing anything; it tells you when the fault happens.
- 2
Check for related codes first
Look for P219B. Related codes often share a cause; a circuit or sensor code usually needs fixing before a performance code like this one.
- 3
Check live data
Watch the related sensor and actuator readings in live data (Fuel injector, Oxygen sensor, Intake manifold) and compare them with expected values in the service information for your vehicle.
- 4
Test the likely causes in order
Start with the most likely cause and work down: One injector clogged or leaking; vacuum leak at one intake runner; low compression on one cylinder. Test before replacing parts.
- 5
Check for recalls and service bulletins
Look up recalls for your exact vehicle with its VIN, and ask a dealer about technical service bulletins (TSBs). Manufacturers sometimes issue software updates or extended warranties for known faults.
- 6
Clear the code and verify the repair
After the repair, clear the code and drive the car under the conditions in the freeze-frame data to confirm it does not return.
P219A repair cost estimate
Estimate, not a quote. Labor times are typical ranges for this code from OBDex, and $125/hr is an assumed rate. Shop rates and labor times vary by vehicle and region. Diagnosis time may be billed separately.
- DIY difficulty
- Hard
- Good DIY job?
- Usually a shop job
Involved testing or major parts. Most owners use a shop.
Parts and systems involved
- Fuel injector
- Oxygen sensor
- Intake manifold
P219A FAQ
What does P219A mean?
P219A means “Bank 1 Air-Fuel Ratio Imbalance”. The fuel-trim values across cylinders on bank 1 differ enough that the bank-average air-fuel ratio is biased — a single cylinder is significantly leaner or richer than the rest. Detected by short-term-fuel-trim variance or by the wide-band O2 sensor harmonic monitor.
Is P219A serious? Can I keep driving?
We rate P219A as moderate severity. Usually yes, for a short time. The car will often drive normally, but get it diagnosed soon. Left alone it can raise fuel use and emissions and will fail an OBD inspection. If you notice rough running, warning lights flashing, overheating or a burning smell, stop driving.
What causes P219A?
The most common causes, from most to least likely: One injector clogged or leaking; Vacuum leak at one intake runner; Low compression on one cylinder. Test before replacing parts, because several causes can set the same code.
How much does it cost to fix P219A?
Typical labor is about $125–$750 at an assumed $125/hour shop rate, plus parts. That is an estimate, not a quote: labor times and rates vary by vehicle and region, and diagnosis may be billed separately.
Can I fix P219A myself?
DIY difficulty is hard. Most owners leave this to a shop because it needs involved testing or specialist tools. Always confirm the cause before buying parts.
Will P219A clear itself?
If the fault was intermittent, the warning may go off once the computer stops seeing it, but the code stays in memory. Fix the cause; clearing the code alone doesn’t repair anything.