P02F9
Cylinder 12 Injector Circuit Range/Performance
Fuel injector circuit
Generic OBD-II
High
What it means
P02F9 means the electrical circuit for the cylinder-12 fuel injector is responding outside its expected range — the injector's current or timing doesn't match what the ECM commands. That cylinder may not fuel correctly, so it can misfire and the engine runs unevenly. This is a per-cylinder injector-circuit fault on engines with 12 cylinders or grouped injector banks.
High
Can I keep driving? Driveable but rough — cylinder 12 may misfire and the engine can feel down on power; extended driving with a dead injector can foul the converter, so fix it promptly.
Common symptoms
What you'll notice
- Check-engine light on
- Misfire or dead miss on cylinder 12
- Rough idle or uneven running
- Reduced power or hesitation
Common causes
Most likely first
- Faulty cylinder-12 injectorLikely
- Open, shorted, or high-resistance wiring to that injectorCommon
- Poor injector connector contact or corrosionCommon
- Fault in the injector driver or control module (FICM/ECM)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the miss is on cylinder 12.
- Inspect the injector connector and harness for that cylinder for damage or corrosion.
- Measure the injector's resistance and compare it to the others.
- Check the injector-driver supply and ground circuits.
- Replace the injector if it's out of spec; re-test before condemning the control module.
FAQ
Quick answers
Is it safe to drive with P02F9?+
You can drive briefly, but a misfiring cylinder dumps raw fuel into the exhaust and can overheat the catalytic converter — don't ignore it.
Can I just clear P02F9?+
It returns once the ECM re-tests the injector circuit; the wiring or injector fault must be repaired first.
Related codes
Often seen with P02F9
Read & clear P02F9 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX