AutoSense AI Knowledge Base
P0300 Code: Random or Multiple Cylinder Misfire
P0300 means the engine computer detected random misfires across multiple cylinders.
The P0300 code means the engine is misfiring, but not consistently in only one cylinder. That makes diagnosis broader than a single-cylinder misfire code.
A random misfire can come from ignition, fuel, air, compression, or sensor problems. It should not be ignored because repeated misfires can quickly damage the catalytic converter.
Symptoms
- Flashing or steady check engine light
- Rough idle
- Shaking during acceleration
- Loss of power
- Poor fuel economy
- Fuel smell from the exhaust
Common Causes
- Worn spark plugs
- Failing ignition coils
- Vacuum leak
- Low fuel pressure
- Dirty or clogged injectors
- Low compression
- Faulty crankshaft or camshaft sensor
Severity
High if the check engine light is flashing. A flashing light means active misfires that can damage the catalytic converter.
Typical Repair Costs
$100 to $2,000+
- Spark plugs may cost $100 to $400 depending on the engine.
- Ignition coils often range from $150 to $700.
- Compression, injector, or timing problems can be much more expensive.
Frequently Asked Questions
Is P0300 serious?
Yes, especially if the check engine light flashes. Stop driving hard and diagnose it promptly.
Can bad spark plugs cause P0300?
Yes. Worn plugs are one of the most common misfire causes.
Can P0300 damage the catalytic converter?
Yes. Unburned fuel from misfires can overheat and damage the converter.
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