P0300
High severityRandom / Multiple Cylinder Misfire Detected
If your check engine light is flashing, pull over safely and stop driving — an active misfire can quickly destroy your catalytic converter. Otherwise, drive only as far as needed to get it checked, as soon as possible.
What does the P0300 code mean?
The P0300 code means one or more cylinders are misfiring at random. “Random” means the misfire isn’t isolated to a single cylinder — if it were, you’d see a cylinder-specific code like P0301 instead.
A misfire means a cylinder isn’t burning its fuel properly, usually due to a spark problem (plugs or coils), a fuel problem, or a vacuum/lean condition affecting several cylinders at once.
Can you keep driving with a P0300 code?
Not recommended. A misfire sends unburned fuel into the exhaust, which can overheat and ruin the catalytic converter – an expensive repair. If the check engine light is flashing, the misfire is active and damaging; stop driving. If it’s steady, drive only to get it checked right away.
What causes a P0300 code?
- Worn spark plugs~30%
- Failing ignition coil(s)~25%
- Vacuum leak or lean condition~15%
- Fuel delivery problem (injectors, pump)~15%
- Low compression or mechanical issue~15%
How to diagnose a P0300 (check these first)
- Check whether the check engine light is flashing — if so, stop driving.
- Inspect and replace old spark plugs (a common, cheap culprit).
- Test ignition coils by swapping one to a different cylinder to see if the misfire follows.
- Scan for companion codes — P0301–P0308 point to a specific cylinder; fuel or vacuum codes point to the cause.
P0300 repair cost
Typical US ranges including parts and labor (varies by vehicle):
| Spark plugs | $50 – $250 |
| Ignition coil | $100 – $350 |
| Vacuum / fuel repairs | $100 – $500+ |
Tools & parts that help
A $20 OBD-II scanner tells you whether the misfire is random or tied to specific cylinders, and flags fuel or vacuum codes – so you fix the real cause, not guess.
See OBD-II scanners & spark plugs ›P0300 — Frequently asked questions
Is it safe to drive with a P0300 code?
It’s not recommended. If the check engine light is flashing, stop driving – an active misfire can destroy the catalytic converter.
Why is a P0300 dangerous?
Unburned fuel from the misfire overheats and can ruin the catalytic converter, turning a cheap fix into an expensive one.
What’s the difference between P0300 and P0301?
P0300 is a random or multiple-cylinder misfire; P0301 (through P0308) points to one specific cylinder.
How much does it cost to fix a P0300?
Often $50-$250 for spark plugs or $100-$350 per ignition coil, more if the cause is fuel or compression related.
Related codes
General guidance based on the standard definition of the P0300 code. A real diagnosis depends on your make, model, mileage and other symptoms. When in doubt, have a professional confirm the cause before replacing expensive parts.