Your car shakes at idle, feels weak when accelerating, and the check engine light flashes. You read the code and see P0300. That means your engine is misfiring. In this article, you’ll learn what P0300 means, what the causes are, and how to systematically fix it.
What does error code P0300 mean?
P0300 stands for "Random/Multiple Cylinder Misfire Detected": the engine misfires on multiple or varying cylinders. If you get a code like P0301, P0302, P0303, or P0304 instead of P0300, the last digit points to the specific cylinder (1, 2, 3, or 4).
A flashing check engine light with P0300 is a warning: do not keep driving, as unburned fuel can damage the catalytic converter.
Symptoms
Unstable idle and shaking. The engine runs unevenly, especially at idle speed.
Power loss and hesitation. The car responds sluggishly or jerks when accelerating.
Flashing check engine light. A flashing light means active misfire; drive calmly and address it quickly.
Possible causes (from cheap to expensive)
Spark plugs or coils. Worn spark plugs or a defective coil are by far the most common cause. Relatively inexpensive to replace.
Spark plug wires or connectors. Poor connections result in a weak spark and thus misfire.
Injectors. A clogged or leaking injector causes incorrect fuel dosing.
Compression or intake leak. A vacuum leak, faulty valve, or low compression can cause misfire. More expensive to diagnose.
How to determine the cause
Use a scanner to read live data and check the misfire counters per cylinder. This way you can see if the misfire comes from a fixed cylinder or is random. If in doubt, swap a spark plug or coil to another cylinder: if the fault moves, you’ve found the part. Always start with the inexpensive suspects (spark plugs and coils) before looking further.
Which scanner do you use for this?
For reading and misfire data per cylinder, an affordable scanner is sufficient:
View the Topdon CarPal → 
View the OBDeleven 3 → 
View the Launch CRP919X →
The Topdon CarPal (around €40) reads the code and live data via your phone. The OBDeleven 3 (around €77) does that plus all modules. The Launch CRP919X (around €440) adds active tests.
Frequently Asked Questions
Can I keep driving with P0300?
If the engine light is flashing, better not; unburned fuel can damage the catalytic converter. Drive calmly home or to the garage and address it quickly.
What is the difference between P0300 and P0301?
P0300 means misfire on multiple or changing cylinders. P0301 to P0306 point to a specific cylinder (the last digit is the cylinder number).
Can a cheap spark plug be the cause?
Yes, very often. Worn spark plugs or a weak coil are the most common causes. Always check those first.
Can I just clear P0300?
Clearing is possible, but if the cause remains, the misfire will come back immediately. First fix the cause, then clear and check the misfire counters.
In short
P0300 means your engine is misfiring on multiple cylinders. The cause is usually a spark plug or coil, not something expensive right away. Read the misfire data per cylinder and start with the inexpensive suspects. Check out the scanners in our diagnostic equipment collection or read how to read and clear fault codes.