How much does it cost to fix P0300?

Repair costs for P0300 typically range from $40 to $800 in the US, depending on the underlying cause. The most common fix is: Worn spark plugs (most common, especially at intervals).

What are the symptoms of P0300?

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.

Check Engine Code

P0300

Random / Multiple Cylinder Misfire Detected

Severity: high DIY difficulty: 2/5 Typical cost: $40–$800

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.

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)

Worn spark plugs (most common, especially at intervals)
Failed ignition coil(s)
Bad or damaged spark plug wires (on engines still using them)
Vacuum leak
Clogged or dead fuel injector
Low fuel pressure
Low compression in one or more cylinders
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.

Confirm P0300 yourself in 60 seconds

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