P0301 on a Hyundai: 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 Hyundai

On a Hyundai, 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 Hyundais?

P0301 is common on Hyundai four-cylinders like the Theta II engines in the Sonata and Santa Fe, where ignition coils and spark plugs are frequent wear items at higher mileage. Direct-injection models can also build up carbon on the intake valves over time. Swapping the coil with another cylinder is a fast way to confirm the diagnosis.

Commonly reported on: Elantra, Sonata, Tucson, Santa Fe.

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: 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	$30–120
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 Hyundai 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 Hyundai 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 Sonatas, Elantras, and Santa Fes.

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

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.