P0285
Cylinder 9 Injector A Circuit Low
Fuel injection — cylinder 9
Generic OBD-II
High
What it means
P0285 means the ECM detected a low-voltage condition — usually a short-to-ground or open — in the cylinder 9 fuel injector control circuit. This is an electrical fault in the injector wiring or coil rather than a fuel-pressure problem, and it typically appears as a misfire and rough running on that one cylinder. It applies to engines with nine or more cylinders.
High
Can I keep driving? Drivable but not ideal — cylinder 9 may misfire, causing rough running and reduced power. Prolonged misfiring can damage the catalytic converter, so repair it soon.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or misfire on cylinder 9
- Reduced power and hesitation
- Possible increased fuel consumption or fuel smell
Common causes
Most likely first
- Short-to-ground or open in the cylinder 9 injector control wiringLikely
- Corroded or loose injector connectorCommon
- Failed injector solenoid (open/shorted coil)Common
- Poor ground or power feed to the injectorLess often
- Faulty ECM injector driver (least likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the cylinder 9 injector connector and wiring for a short-to-ground or open.
- Measure the injector coil resistance and compare with the other injectors.
- Check the control circuit and power feed for continuity and correct voltage.
- Replace the injector if its coil is out of spec, or repair the wiring fault.
- Clear the code and confirm the misfire and code stay gone on a road test.
FAQ
Quick answers
Is it safe to drive with P0285?+
Short-term yes, but the affected cylinder can misfire, and sustained misfiring can overheat and damage the catalytic converter. Fix it promptly.
Can I just clear P0285?+
It returns quickly if the injector circuit fault is still there. Repair the wiring or injector first.
Related codes
Often seen with P0285
Read & clear P0285 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