P219A Bank 1 Air-Fuel Ratio Imbalance
On bank 1, one or more cylinders is running noticeably richer or leaner than the others, even if the average mixture looks fine.
Common causes
- Leaking or clogged fuel injector
- Intake leak at one cylinder
- Faulty air-fuel ratio sensor
- A misfire
Symptoms
- Often none besides the check engine light
- Sometimes rough idle or hesitation
Can I drive with it?
Usually safe to drive short term. Get it checked before it damages the catalytic converter.
Tip: On some Honda and Toyota engines a service bulletin covers this code – ask a dealer before replacing parts.
Which scanner reads it?
Any OBD2 scanner reads it. Live fuel trim and air-fuel sensor data help, but pinning down the cylinder often takes a shop's injector balance test.
Budget tools like the ANCEL AD310 read it; tools with live data and graphing – like the BlueDriver or OBDLink MX+ – help you find the cause. Not sure which fits you? Try the Find My Scanner quiz.
In the data
How common is it? In New York City’s taxi and for-hire fleet – high-mileage cars, mostly hybrids – P219A was the #15 code found on cars failing inspection in 2020–21 (1.2% of codes found).
Of the vehicle complaints owners filed with NHTSA from 2015 to 2025, 39 quote P219A – most often from Honda, Ford, Toyota owners. Complaints lean toward serious problems, so treat this as a sign of how often the code turns up in real reports, not how often cars get it.
Both sources are compared on the Trends page.
Related codes
General information to help you understand a code – not a diagnosis. Your car’s service information or a qualified mechanic has the final word. See how we research.