P0301 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 P0301 means on a Subaru

On a Subaru, P0301 means the engine computer has detected that cylinder 1 is not firing properly and is failing to contribute its share of power. Because the code points to one cylinder, the fault is usually specific to cylinder 1, such as its spark plug, ignition coil, or fuel injector.

Is P0301 common on Subarus?

P0301 is common on higher-mileage Subarus like the Outback, Forester, and Impreza. Because Subaru uses flat boxer engines, the spark plugs sit on the sides of the engine and take more labor to reach than on other cars. Ignition coils and spark plugs are the usual causes, and a coil swap test is a fast way to confirm which part is bad.

Commonly reported on: Outback, Forester, Impreza, Crosstrek.

Symptoms

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

Common causes

most common: Worn or fouled spark plug in cylinder 1
common: Failing ignition coil for cylinder 1
common: Clogged or leaking fuel injector in cylinder 1
less common: Vacuum leak near the intake
less common: Low compression in cylinder 1 from engine wear

How to fix it

Fix	DIY?	Typical cost
Replace the spark plug in cylinder 1	Yes	$40–180
Replace the ignition coil for cylinder 1	Yes	$100–300
Clean or replace the fuel injector in cylinder 1	Mechanic	$150–600
Run a compression test to rule out internal engine wear	Mechanic	$100–200

Frequently asked questions

Is it safe to drive my Subaru with a P0301 code?

Only if the light is steady and the car runs fine. A flashing light means a severe misfire, so stop driving and get it towed.

Why does my Subaru misfire on cylinder 1?

The spark plug, ignition coil, or fuel injector for that cylinder is usually the problem. These parts wear out over time on Outbacks, Foresters, and Imprezas.

How much does it cost to fix P0301 on a Subaru?

Plugs and coils run about $40–$300. Because boxer engines make plugs harder to reach, labor can add to the bill.