P0300
Random/Multiple Cylinder Misfire Detected
Ignition / misfire
Generic OBD-II
High
What it means
P0300 means the engine is misfiring on random or multiple cylinders — fuel isn't burning properly, so the engine runs rough and loses power. It's one of the more serious common codes: sustained misfires can overheat and destroy the catalytic converter.
High
Can I keep driving? Not for long — a flashing check-engine light means an active misfire; drive as little as possible until fixed to avoid converter damage.
Common symptoms
What you'll notice
- Check-engine light on (often flashing during an active misfire)
- Rough idle, shaking, or stalling
- Reduced power and hesitation on acceleration
- Increased fuel consumption
Common causes
Most likely first
- Worn spark plugs or failing ignition coilsLikely
- Clogged or leaking fuel injectors / low fuel pressureCommon
- Vacuum leak in the intakeCommon
- Failing sensors (coolant temp, MAF, O2)Less often
- Mechanical — low compression or valvetrain wearLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check for cylinder-specific codes (P0301-P0308) to pinpoint the miss.
- Inspect and replace worn spark plugs and coils first — the most common cause.
- Check fuel delivery: injectors, fuel pressure, and filter.
- Test for vacuum leaks around the intake.
- If it persists, run a compression test for mechanical causes. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0300?+
No — especially with a flashing light. Active misfires can quickly damage the catalytic converter.
Can I just clear the code?+
You can, but it returns within a few drive cycles until the misfire cause is repaired.
Related codes
Often seen with P0300
Read & clear P0300 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX