P0301 on a Lexus: 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 Lexus

On a Lexus, 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 Lexuss?

P0301 is less common on Lexus models but shows up on higher-mileage ES, RX, and IS models, mostly from worn spark plugs or aging ignition coils. Lexus uses Toyota-built engines like the 3.5L V6, which are generally reliable but need spark plug service on schedule. Because only one cylinder is involved, a coil swap test with another cylinder usually finds the bad part quickly.

Commonly reported on: ES, RX, IS, GS.

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: 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	$100–350
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 Lexus 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 Lexus 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, most often on high-mileage ES, RX, and IS models.

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

A spark plug is the cheapest fix, usually under $200. A coil costs more, and a fuel injector is the most expensive of the three.