StopOrDrive

Enter a 5-character code such as P0420, P0301, or P0457.

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Codes starting with P are engine and transmission, B are body, C are chassis, and U are network communication. A 0 as the second character means a generic code shared by all makes; a 1 means a manufacturer-specific code, so its meaning depends on your brand.

A steady check engine light usually means get it checked soon. A flashing check engine light means an active misfire: reduce speed and stop driving as soon as it is safe.

That doesn't look like an OBD-II code

A valid code is one letter (P, B, C, or U) followed by four characters, for example P0420.

P0301 Cylinder 1 misfire detected

Can I drive with P0301?

Drive soon

OK to drive for now, but get it fixed within days to a couple of weeks, or the damage and the bill can grow.

With a steady light, drive gently and get it checked soon. Misfires waste fuel and slowly damage the catalytic converter.

If your check engine light is flashing, treat this as Stop now: an active misfire dumps unburned fuel into the exhaust and can destroy the catalytic converter within miles.

What does P0301 mean?

Cylinder 1 is not burning its fuel properly, so the engine computer detected that cylinder stumbling. You may feel shaking at idle or a loss of power. Cylinder 1 is usually at the front of the engine; your owner's manual or a search for your model shows where.

What causes P0301?

Ignition parts fail most often. Swap the cylinder 1 coil with a neighbor and clear the code; if the misfire follows the coil, replace it.

  1. Worn spark plug in cylinder 1
  2. Faulty ignition coil on cylinder 1
  3. Clogged or failed fuel injector for cylinder 1
  4. Vacuum leak near that cylinder
  5. Low compression from a valve or head gasket problem

How much does it cost to fix P0301?

$100 – $600

Spark plugs: $100–$300 at a shop. Ignition coil: $150–$400. Fuel injector: $250–$600. Compression problems cost $1,000 or more. The coil swap test is free, and new plugs are a sensible first step if they are due for replacement.

What are the symptoms of P0301, and how can I confirm it?

Expect a rough or shaking idle, hesitation when accelerating, and worse fuel economy. To confirm, pull the cylinder 1 spark plug and look for wear, oil, or heavy carbon, and check the coil boot for cracks. If P0300 or other cylinder codes appear too, look for a cause shared by the whole engine.

Will P0301 fail an emissions test, and should I clear it?

It fails any OBD-II based inspection while the light is on, and an ignored misfire can ruin the catalytic converter and set P0420. After a repair, clear the code and drive normally for a few days. If P0301 returns, have the injector and compression tested.

Confirm the code yourself

A low-cost scanner lets you read the code, clear it, and see if it comes back before paying for a diagnosis.

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