What does code P0300 mean on a Mazda and is it safe to drive?
P0300: Random/Multiple Cylinder Misfire Detected. Here's what it means on your Mazda, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
The PCM has detected misfires across multiple cylinders. This can cause damage to the catalytic converter if driven for long.
Common causes for your Mazda
- Worn spark plugs or ignition coils
- Clogged or bad fuel injectors
- Low compression
- Vacuum leak, bad MAF, or fuel delivery issue
Symptoms
- Check Engine Light (often flashing under load)
- Rough idle, shaking, loss of power
- Possible smell of unburned fuel
Typical fixes
- Replace spark plugs and coils as needed
- Clean or replace fuel injectors
- Fix vacuum/fuel issues
- Compression test if no obvious cause
Repair cost range
For a Mazda, repairs for P0300 often fall between $150 and $1200, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Mazda
Mazda P0300 on SkyActiv-G 2.5L engines is relatively uncommon. When it occurs after 100k miles, direct injection intake valve carbon buildup is the most likely cause—the Mazda SkyActiv uses DI-only fueling (no port injection), which accelerates carbon buildup. On Mazdaspeed3 2.3T, P0300 during hard acceleration indicates a boost leak. RX-8 13B Wankel engine P0300 is a completely different failure mode—Wankel apex seal wear causes systematic misfires and the 13B is unusually sensitive to oil viscosity and cold-start technique.
Most commonly affected models