Misfire codes, in plain English

P0301 through P0308 point to a specific cylinder. P0300 means several at once.

What a misfire is

A misfire means a cylinder isn't burning its fuel-and-air mixture cleanly. You might feel shaking, a rough idle, or a loss of power. The last digit tells you which cylinder — P0303 is cylinder 3.

What it usually costs

The most common and cheapest causes are worn spark plugs or ignition coils — often a few hundred dollars. If the cause is a fuel injector or an internal engine problem, it climbs from there. If a shop quotes you thousands for 'spark plugs,' that's your cue to get a second opinion.

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