P0285 Code: Cylinder 9 Fuel Injector Circuit Low
🟠 Moderate severity · drivable
Drivable, but cylinder 9 may misfire and the engine can run rough. Have it checked soon.
What P0285 means
The fuel injector circuit for cylinder 9 is reading lower voltage than the computer expects. That usually means the circuit is open or shorted to ground, so the computer cannot control fuel delivery to that cylinder correctly.
Symptoms
- Check engine light on
- Rough idle or misfire
- Loss of power
- Poor fuel economy
Common causes
- most common: Open or shorted wiring in the cylinder 9 injector circuit
- common: Faulty fuel injector on cylinder 9
- common: Loose or corroded injector connector
- rare: Injector driver fault inside the engine computer
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect and clean the cylinder 9 injector connector | Yes | $0–10 |
| Repair open or shorted injector wiring | Mechanic | $50–200 |
| Replace the cylinder 9 fuel injector | Mechanic | $100–300 |
Frequently asked questions
Can I drive with P0285?
Yes, but cylinder 9 may misfire and the engine can run rough. Fix it soon to avoid damaging the catalytic converter.
What causes a P0285 code?
Usually a wiring problem in the cylinder 9 injector circuit, or a faulty injector.
How much does it cost to fix P0285?
Typically $100–$300 for a new injector, or less if it is just a wiring or connector repair.
Related codes
P0286
P0286 Code: Cylinder 9 Fuel Injector Circuit High
P0287P0287 Code: Cylinder 9 Fuel Injector Contribution/Balance
P0309P0309 Code: Cylinder 9 Misfire Detected
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.