Cylinder 8 - Injector Leaking
What it means
P02B9 means the ECM has determined that cylinder 8's fuel injector is leaking — passing more fuel than commanded, so the cylinder runs rich. It usually comes from a worn injector, a bad seal, or excessive fuel pressure. Beyond rough running and a rich exhaust, a leaking injector can foul the spark plug, wash lubricating oil off the cylinder wall, and overload the catalytic converter, so it should be repaired promptly.
Can I keep driving? Driveable but running rich on cylinder 8 — expect rough running; a badly leaking injector can foul the plug, wash oil off the cylinder wall, and stress the converter.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or hesitation
- Rich exhaust smell or black smoke
- Possible misfire on cylinder 8
Common causes
Most likely first
- Leaking or failed cylinder-8 fuel injector (worn pintle or seat)Likely
- Deteriorated injector seal or O-ringCommon
- Excessive fuel pressure forcing the injector to weepCommon
- Carbon-fouled injector not sealingLess often
- Faulty ECM/injector driver (least likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame and fuel-trim data to confirm cylinder 8 is running rich.
- Perform an injector leak-down or balance test on cylinder 8.
- Check fuel pressure against spec to rule out an over-pressure condition.
- Inspect the cylinder-8 spark plug for fuel fouling.
- Replace the leaking injector (and seals). Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P02B9?+
Can I just clear P02B9?+
Related codes
Often seen with P02B9
Read & clear P02B9 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.