TorqueMech OBD Code Guide
P0300 - Random/Multiple Cylinder Misfire Detected
The ECM detected misfires occurring on multiple cylinders.
Severity
Medium-High
Drivability
Rough idle, hesitation, flashing MIL possible
Typical Cost
$150 - $900+
Code Meaning
The ECM detected misfires occurring on multiple cylinders.
What You May Notice
- Rough idle or random stumble
- Hesitation under acceleration
- Flashing check engine light during heavier load
- Reduced fuel economy and poor throttle response
Common Causes
Worn spark plugs or ignition coils
Vacuum leak or intake leak
Low fuel pressure
Dirty MAF sensor
Injector issue
Quick Checks
- Check for other codes (P0301–P0308)
- Inspect plugs and coils (swap coil test)
- Look for vacuum leaks (cracked hoses, intake boot)
- Check fuel trims / fuel pressure if available
- Inspect MAF and air filter
Ignition / Fuel Trim Checks
- Review misfire counters and fuel trims on the scan tool
- Check coil power supply and shared grounds on affected cylinders
- Inspect injector connectors and MAF wiring before replacing parts
- Verify no intake leak is skewing bank-to-bank airflow readings
Likely Repairs
Use test results to confirm the fault before pricing the repair.
Ignition coil replacement
Estimator-ready next step for a confirmed repair path.
Spark plug replacement
Estimator-ready next step for a confirmed repair path.
Fuel injector cleaning or replacement
Estimator-ready next step for a confirmed repair path.
Vacuum leak smoke test
Estimator-ready next step for a confirmed repair path.
Mass air flow sensor replacement
Estimator-ready next step for a confirmed repair path.
Related Cost Guides
Use these only when testing has already pointed you to a matching repair path.
Spark Plug Replacement Cost
Useful when testing confirms worn or fouled plugs are driving the misfire.
Next Steps
Move from the code to a diagnosis path, then into repair pricing once the fault is confirmed.