P0301 on a Mazda: 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 Mazda

On a Mazda, P0301 means the engine computer has detected that cylinder 1 is not firing properly and is failing to contribute its share of power. Because it is a single-cylinder code, the fault is usually something specific to cylinder 1, like its spark plug, ignition coil, or fuel injector.

Is P0301 common on Mazdas?

P0301 is common on Mazda's SKYACTIV engines in the Mazda3, Mazda6, and CX-5, where iridium spark plugs last a long time but eventually need replacing. Ignition coils and fuel injectors are the other usual suspects on these direct-injection engines. Because only one cylinder is involved, a coil swap with another cylinder quickly confirms the diagnosis.

Commonly reported on: Mazda3, Mazda6, CX-5, CX-9.

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 spark plug in cylinder 1
common: Failing ignition coil for cylinder 1
common: Clogged or leaking fuel injector in cylinder 1
less common: Carbon buildup on intake valves on direct-injection engines
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	$30–150
Replace the ignition coil for cylinder 1	Yes	$80–280
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 Mazda 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 Mazda 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 Mazda3s, Mazda6s, and CX-5s.

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

A spark plug is the cheapest fix, usually under $150. A coil costs more, and a fuel injector is the most expensive of the three.