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P0300 Random/Multiple Cylinder Misfire Detected
What it means
The engine computer detected misfires that aren't limited to one cylinder. Something common to several cylinders (fuel, air, ignition) is likely at fault.
Severity: High
Can I drive it? Avoid driving if the check engine light is flashing — unburned fuel can overheat and ruin the catalytic converter. Steady light: drive gently to get it fixed.
Common causes (most likely first)
- Worn spark plugs
- Vacuum leak
- Low fuel pressure / weak fuel pump or clogged filter
- Faulty ignition coil(s) or plug wires
- Dirty MAF sensor
- Mechanical issue (low compression, timing)
Likely fixes
- Replace spark plugs if due
- Check for vacuum leaks
- Test fuel pressure
- Check coils/wires; clean MAF sensor
- Compression test if the above check out
DIY parts cost
$20–$300
Approximate estimate
Shop repair cost
$100–$1,000+
Approximate estimate, parts + labor
DIY difficulty
Easy to Moderate
Varies by vehicle
Cost ranges are rough, approximate U.S. estimates and vary widely by vehicle, region, and parts brand. Always confirm the diagnosis before buying parts.
Parts you may need
- Spark plugsCheck price
- Ignition coilCheck price
- Spark plug wiresCheck price
- MAF sensor cleanerCheck price
- Fuel filterCheck price
Affiliate links are placeholders. Verify fitment for your year/make/model.