P0305 on a Subaru: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

If the check engine light is flashing, stop driving — a severe misfire can damage the catalytic converter. A steady light is usually safe for a short drive to a shop.

What P0305 means on a Subaru

On a Subaru, P0305 means the engine computer detected a misfire on cylinder 5. Only Subaru's six-cylinder boxer engines have a cylinder 5 — four-cylinder models don't. Because the code names one cylinder, the cause is usually its ignition coil, spark plug, or injector.

Is P0305 common on Subarus?

P0305 appears on Subaru H6 models like the Outback and Tribeca, which use the 3.6L six-cylinder boxer engine. Worn spark plugs and failing ignition coils are the most common causes at higher mileage. Clogged or leaking injectors are less common but possible.

Commonly reported on: Outback, Tribeca, Legacy.

Symptoms

Check engine light on (flashing if severe)
Rough idle or shaking
Loss of power or hesitation
Poor fuel economy

Common causes

most common: Worn or fouled spark plug on cylinder 5
common: Failing ignition coil on cylinder 5
less common: Clogged or leaking fuel injector
less common: Wiring or connector issue at the coil
less common: Low compression from engine wear

How to fix it

Fix	DIY?	Typical cost
Replace the spark plug on cylinder 5 (or all plugs)	Yes	$50–180
Replace the ignition coil on cylinder 5	Yes	$90–280
Replace or clean the cylinder 5 injector	Mechanic	$250–600
Run a compression test if the misfire returns	Mechanic	$100–200

Frequently asked questions

Which Subarus have a cylinder 5?

Only six-cylinder models like the Outback 3.6R and the Tribeca. Four-cylinder Subarus set P0301–P0304 instead.

What usually causes P0305 on a Subaru?

A worn spark plug or a failing ignition coil are the most common causes. On the H6, plugs sit lower on the engine, so the job takes a bit more work than on a 4-cylinder.

Can I keep driving my Subaru with P0305?

A steady light is usually fine for short trips. A flashing light means a severe misfire, so stop and have it towed.