P0300 on a Nissan: 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 P0300 means on a Nissan

On a Nissan, P0300 means the engine computer sees misfires jumping between cylinders instead of on one fixed cylinder. A misfire means a cylinder is not burning its fuel properly, which wastes gas and can damage the catalytic converter if left alone.

Is P0300 common on Nissans?

P0300 shows up on Nissan 4-cylinders like the Altima, Sentra, and Rogue, especially the 2.5L engine. Failing ignition coils are a well-known Nissan pattern, and worn spark plugs are another top cause. Vacuum leaks and clogged injectors round out the usual list.

Commonly reported on: Altima, Sentra, Rogue, Pathfinder.

Symptoms

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

Common causes

most common: Failing ignition coils
common: Worn or fouled spark plugs
common: Vacuum leak
less common: Clogged fuel injectors or low fuel pressure
less common: Low compression from engine wear

How to fix it

Fix	DIY?	Typical cost
Replace failing ignition coils	Yes	$100–350
Replace worn spark plugs	Yes	$60–200
Find and repair vacuum leaks	Yes	$10–100
Run a compression test to rule out internal engine wear	Mechanic	$100–200