What Does Code P0300 Mean and How Do I Fix Random Misfires?
Quote from DIYDan on June 9, 2025, 2:15 pmMy check engine light came on and I scanned it with my OBD2 scanner. It showed Code P0300 – Random/Multiple Cylinder Misfire Detected. The engine feels shaky, especially at idle. What could be causing this and how can I fix it?
My check engine light came on and I scanned it with my OBD2 scanner. It showed Code P0300 – Random/Multiple Cylinder Misfire Detected. The engine feels shaky, especially at idle. What could be causing this and how can I fix it?
Quote from Kevin Nicholas on June 10, 2025, 7:53 amP0300 means your engine's computer has detected random misfires across multiple cylinders. It’s one of the more common codes but can be tricky since it’s not tied to a specific cylinder like P0301 or P0302.
🔍 Common Causes:
Faulty spark plugs or ignition coils
Vacuum leaks (cracked hoses, intake gasket issues)
Fuel delivery problems – weak fuel pump, clogged injectors
Low fuel pressure
EGR valve malfunction or PCV issues
Bad MAF sensor (Mass Air Flow)
🛠️ Fix Suggestions:
Start with the basics: inspect and replace spark plugs & ignition coils
Use carb cleaner or smoke test to find vacuum leaks
Clean or replace the MAF sensor
Run a fuel pressure test
Scan for other codes that might help narrow it down
Clearing the code without fixing the cause will just bring the light back, so it's best to diagnose step-by-step. Let us know your car model/year and we can guide further!
P0300 means your engine's computer has detected random misfires across multiple cylinders. It’s one of the more common codes but can be tricky since it’s not tied to a specific cylinder like P0301 or P0302.
🔍 Common Causes:
-
Faulty spark plugs or ignition coils
-
Vacuum leaks (cracked hoses, intake gasket issues)
-
Fuel delivery problems – weak fuel pump, clogged injectors
-
Low fuel pressure
-
EGR valve malfunction or PCV issues
-
Bad MAF sensor (Mass Air Flow)
🛠️ Fix Suggestions:
-
Start with the basics: inspect and replace spark plugs & ignition coils
-
Use carb cleaner or smoke test to find vacuum leaks
-
Clean or replace the MAF sensor
-
Run a fuel pressure test
-
Scan for other codes that might help narrow it down
Clearing the code without fixing the cause will just bring the light back, so it's best to diagnose step-by-step. Let us know your car model/year and we can guide further!
Quote from Deleted user on June 10, 2025, 8:00 amHad this on my 2013 Nissan Altima — turned out to be bad ignition coils. Replaced all 4 and problem went away. If your mileage is high, it’s worth replacing coils and plugs together.
Had this on my 2013 Nissan Altima — turned out to be bad ignition coils. Replaced all 4 and problem went away. If your mileage is high, it’s worth replacing coils and plugs together.
Quote from AutoFixerMike on June 16, 2025, 8:49 amDon’t forget to check the MAF sensor. Dirty MAFs can cause misfire codes and rough idle. I just cleaned mine with MAF cleaner spray and it fixed the issue. Easy 10-minute job!
Don’t forget to check the MAF sensor. Dirty MAFs can cause misfire codes and rough idle. I just cleaned mine with MAF cleaner spray and it fixed the issue. Easy 10-minute job!