P0305 Code: Cylinder 5 Misfire Detected

🟠 Moderate severity · drivable

Brief driving with a steady light is usually fine, but repair it soon to avoid catalytic-converter damage — and stop if the light flashes.

What P0305 means

The engine computer has detected a misfire on cylinder 5. Because this is a single-cylinder code, the cause is almost always confined to cylinder 5 — its spark plug, ignition coil, or injector — unlike P0300, where a random misfire across cylinders points to a shared cause such as fuel pressure or an air leak.

Symptoms

Check engine light on (flashing when severe)
Shaking or rough idle
Reduced power and hesitation
Poorer fuel economy

Common causes

most common: Worn or fouled spark plug on cylinder 5
common: Failing ignition coil or plug wire for cylinder 5
common: Clogged or leaking fuel injector on cylinder 5
less common: Low compression in cylinder 5 (worn rings, valve, or gasket)

How to fix it

Fix	DIY?	Typical cost
Swap cylinder 5's plug and coil with another cylinder to confirm the misfire follows the parts	Yes	$0–20
Replace the cylinder 5 spark plug	Yes	$10–50
Replace the cylinder 5 ignition coil	Yes	$50–200
Have cylinder 5 compression-tested	Mechanic	$100–200

Frequently asked questions

Does P0305 only affect cylinder 5?

Yes. A single-cylinder misfire means the fault is nearly always on that cylinder's plug, coil, or injector. If the misfire moves between cylinders, expect P0300 rather than P0305.

How do I isolate a P0305 fast?

Move cylinder 5's spark plug and coil to a different cylinder and re-scan. If the misfire travels with them, you've found the culprit; if it stays on 5, check the injector and compression.

Can I keep driving with a P0305?

Short term with a steady light, yes — but fix it promptly, since unburned fuel can harm the catalytic converter. A flashing light means stop and tow.