P0278 — Cylinder 6 Injector Circuit High
Drive with caution — fix soon.
What P0278 means
This code means the computer detected an abnormally high voltage in the wiring or circuit that controls cylinder 6's fuel injector. It usually points to an open circuit, a bad connector, or a failing injector that isn't switching properly. It's often fixable by repairing the circuit or replacing the injector, without major engine work.
Common symptoms
- Check engine light is on
- Rough idle or engine shaking
- Engine misfire or hesitation
- Noticeable loss of power
- Increased fuel consumption
Common causes
- Open or broken injector wiring for cylinder 6
- Corroded or loose injector connector
- Failed fuel injector on cylinder 6
- Short to power in the injector circuit
- Faulty engine control module (ECM) driver
Typical repair cost
$120 – $450
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0278 code?
For short trips, usually yes, but you shouldn't rely on it. The affected cylinder may run poorly and cause rough idling or lost power. Have it checked soon to prevent converter or engine damage.
How much does it cost to fix a P0278 code?
Repairs typically range from about $120 to $450. A simple wiring or connector fix is on the lower end, while replacing the injector with diagnostic labor costs more.
Is a P0278 code serious?
It's a moderate concern. The car usually still runs, but a misfiring cylinder hurts fuel economy and stresses the engine. It's best to fix it before the issue grows.
What does the injector circuit high reading mean for cylinder 6?
It means the computer sees too much voltage in the injector control circuit, suggesting an open or shorted wire or a faulty injector. The injector may not be firing properly, so cylinder 6 isn't getting the right fuel.