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OBD-II CODE / Misfire

P0300 · Random or multiple cylinder misfire

The computer detected a misfire pattern that was random or involved multiple cylinders.

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Start here

If the light is flashing while you drive, ease off and pull over safely. Follow the owner’s manual and arrange help if the light keeps flashing or the car runs badly.

Part of the Misfire system guide.

Save the pattern

Record all cylinder codes, engine speed and load from the freeze frame. Note whether it happened on a cold start, at idle or under load. A scan tool with misfire counters can help a technician identify which cylinders to test first.

Sort the possible causes

Ignition, fueling and mechanical problems can all produce a misfire. When several cylinders are involved, check for a shared issue before buying parts for each cylinder.

A vehicle-specific example

GM documents valve deposits or sticking valves as one possible source of rough running and multiple misfire codes in covered gasoline vehicles. That bulletin includes a defined set of conditions and service steps.

Sources

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