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.
Stop driving if: the check engine light is flashing, or the car starts running noticeably worse
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?
Listed in the order most shops would check them — cheapest and most likely first, not as statistical odds. The real cause varies by year, make, model and engine.
- Low compression or mechanical issueCheck 1st
- Fuel delivery problem (injectors, pump)Check 2nd
- Vacuum leak or lean conditionCheck 3rd
- Failing ignition coil(s)Check last
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):
Costs vary a lot by vehicle and region. These are typical US ranges including parts and labor — treat them as a ballpark for the conversation with your shop, not a quote.
| Spark plugs | – 0 |
| Ignition coil | 0 – 0 |
| Vacuum / fuel repairs | 0 – 0+ |
Tools & parts that help
A 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 top-rated OBD-II scanners ›As an Amazon Associate I earn from qualifying purchases. This costs you nothing extra and never changes what we recommend.
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 -0 for spark plugs or 0-0 per ignition coil, more if the cause is fuel or compression related.
Related codes
General guidance based on the standard SAE definition of the P0300 code. A real diagnosis depends on your make, model, year, engine and other symptoms. This is not a substitute for a professional inspection — when in doubt, have a technician confirm the cause before replacing expensive parts.