P0300

Diagnostic Guide: P0300 — Random/Multiple Cylinder Misfire Detected OBD-II

PowertrainIgnition SystemCritical

Quick Answer

What P0300 Means

Your engine has random misfires across multiple cylinders. The engine isn't burning fuel properly in one or more cylinders.

Most Likely Cause

Worn spark plugs or ignition coils

This is the cause in approximately 50-60% of cases

Easy DIY Fix

Spark plug replacement is one of the easiest DIY repairs. Most people can do this.

Urgent

Driving with misfires can damage your catalytic converter. Fix as soon as possible.

Driving Not Recommended

Driving with misfires can damage your catalytic converter. Fix as soon as possible.

Estimated Repair Cost

$100 - $400

At a repair shop

$20 - $100

DIY (parts only)

Parts You May Need

Showing 3 of 4 parts

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Detailed Diagnostic Information

Important Disclaimer

This information is for educational purposes only. We are not licensed mechanics. Always consult a certified mechanic for diagnosis and repair. Improper repairs can be dangerous.

Last updated: 2025-11-26

P0300 diagnostic guide by MechanicGPT