P0285 — Cylinder 8 Contribution/Balance Fault
Drivable short-term, but fix now to avoid damage.
What P0285 means
This code means cylinder 8 is producing less power than the other cylinders, so the engine computer flags it as out of balance. It usually points to a weak or clogged fuel injector, low compression, or an ignition fault on that cylinder. It's a common code on larger engines, and once the cause is found it's often fixable without tearing into the engine.
Common symptoms
- Check engine light is on
- Rough idle or noticeable engine shaking
- Loss of power or sluggish acceleration
- Vibration felt through the cabin
- Slightly worse fuel economy
Common causes
- Weak, clogged, or failing injector on cylinder 8
- Low compression in cylinder 8 (worn rings or valves)
- Faulty spark plug or ignition coil on that cylinder (gas engines)
- Vacuum leak affecting cylinder 8
- Wiring or connector fault at the injector
Typical repair cost
$150 – $900
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0285 code?
For short trips, usually yes, but you shouldn't depend on it. The engine is unbalanced, which can worsen and damage other parts. If the light is flashing or the car shakes badly, stop driving and get help right away.
How much does it cost to fix a P0285 code?
It varies with the cause. An injector or ignition coil replacement often runs $150 to $500, while compression repairs can reach $900 or more. Diagnosis comes first so you only pay for what's needed.
Is a P0285 code serious?
It's fairly serious. A cylinder not pulling its weight means lost power and potential misfiring that can damage the catalytic converter over time. Address it promptly.
Why does only cylinder 8 set this code?
The computer measures how much each cylinder contributes to engine rotation. When cylinder 8 lags behind the rest, it flags that specific cylinder. The repair focuses on why that one is weak, usually fuel, compression, or ignition.