P0300

What P0300 means

P0300 means the ECM detected misfires across several cylinders or can't localize which cylinder is misfiring. When P0300 appears with P0301-P0308, the specific cylinder codes identify individual misfires.

Vehicle-specific P0300 guides

P0300 can mean different things on different vehicles. Pick your make for engine-family specifics:

Symptoms

• Check engine light (often flashing — flashing means catalytic damage is happening now)
• Rough idle, shuddering
• Loss of power
• Hesitation or stumble under load
• Smell of unburned fuel

Likely causes (most common first)

1. Worn spark plugs (most common, especially at intervals)
2. Failed ignition coil(s)
3. Bad or damaged spark plug wires (on engines still using them)
4. Vacuum leak
5. Clogged or dead fuel injector
6. Low fuel pressure
7. Low compression in one or more cylinders
8. Timing issue (stretched chain, skipped tooth)

Can I keep driving?

If the CEL is flashing, stop driving — flashing means active catalyst damage. A steady light with mild misfire is drivable short distances, but don't delay the fix.

Typical repair cost

DIY fixes can start near $40 (parts only). Shop repairs for P0300 typically run up to $800 depending on the underlying cause and vehicle. Start with the most common cause — Worn spark plugs (most common, especially at intervals) — before throwing parts at it.

Symptoms that match P0300

If you got here from a search query, one of these might describe what your car is actually doing:

• Check Engine Light Flashing — What It Means and What to Do
• Check Engine Light On (Solid, Not Flashing) — Causes & Next Steps
• Rough Idle — Causes & How to Fix It
• Engine Misfire — Symptoms, Codes, and What to Fix First
• Car Stalling While Driving — Top Causes
• White Smoke from Exhaust — What It Means

Recommended parts & tools for P0300

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Related codes

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