Ignition and misfire
P0300 — Random/Multiple Cylinder Misfire Detected
The ECU detects misfires that move between cylinders or happen in several cylinders at the same time. The engine runs rough and unburned fuel may reach the catalytic converter.
Common causes
- Worn spark plugs or weak ignition coils
- Vacuum leak or lean mixture
- Low fuel pressure, dirty injectors or bad fuel
- Faulty MAF, MAP or crankshaft sensor
- EGR valve stuck open or low compression
Symptoms
- Rough idle and shaking
- Loss of power and hesitation
- Flashing check engine light
- Higher fuel use and fuel smell
How to check
- Read freeze-frame data and check which cylinders also have individual misfire codes
- Inspect spark plugs and ignition coils
- Check fuel trims, look for vacuum leaks and test fuel pressure
- Check sensors and the EGR valve; test engine compression if needed
Can you keep driving?
Avoid driving if the check engine light is flashing: active misfire can quickly destroy the catalytic converter. Short, light-load trips only otherwise.
Codes in the same family
P0300 to P0308 all describe misfires: P0300 is a random or multiple-cylinder misfire, while P0301 to P0308 name cylinder 1 to cylinder 8.
Related codes
Frequently asked questions
- What does P0300 mean?
- The ECU sees misfires that are random or in several cylinders at once.
- What is the most common cause of P0300?
- Worn spark plugs and ignition coils, and vacuum leaks, are among the most common.
General reference information. It does not replace a diagnosis on your own vehicle. The same code can have different causes depending on make, model year and engine; check the manufacturer's documentation or ask a technician with a scan tool.