What it means
Injection timing performance for cylinder 12 is more advanced than the expected range.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine control module coordinates fuel delivery to cylinder 12 through its injector and monitors whether injection timing behaves as expected. This code sets when the timing for cylinder 12 is detected as too far advanced, which can result from an injector response problem or a fault in its control circuit or fuel delivery.
Common causes
Most likely first.
- Injector wear, sticking, or restricted flow
- Fault in cylinder 12 injector wiring or connector
- Injector driver or control circuit fault
- Fuel pressure or delivery problem affecting injector response
Symptoms
- Check engine light on
- Rough idle or vibration
- Reduced power or uneven acceleration
- Increased fuel consumption
How to diagnose it
- Record freeze-frame data and compare cylinder 12 misfire or contribution data with the other cylinders to see when the timing fault occurs.
- Inspect the cylinder 12 injector connector and wiring for loose pins, corrosion, chafing, or heat damage.
- Check whether cylinder 12 injector command or timing data differs from other cylinders under the conditions captured in the freeze frame.
- Test the cylinder 12 injector control circuit and driver for continuity, shorts, and correct operation according to the manufacturer's specification.
- Check fuel pressure and delivery under the conditions when the fault occurs, then assess the cylinder 12 injector for sticking, wear, or restricted flow.
Common fixes
- Repair damaged wiring or secure and clean the cylinder 12 injector connector.
- Correct a fuel delivery or pressure problem affecting injector response.
- Repair a fault in the cylinder 12 injector control circuit or driver.
- Replace or service the cylinder 12 injector if testing confirms sticking, wear, or restricted flow.
Can I keep driving?
If the engine runs roughly or loses power, avoid hard acceleration and long trips; continued misfiring or uneven fueling can worsen drivability and increase emissions. Stop driving if the engine shakes severely or the check-engine light flashes.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.