If your engine is misfiring, it means one or more cylinders are not firing properly. This causes uneven running, shaking, loss of power, and poor fuel efficiency. Misfires can be caused by ignition, fuel, or air supply issues, and ignoring them can lead to severe engine or catalytic converter damage.

What does it mean if the engine is misfiring?

A misfire occurs when the air-fuel mixture in a cylinder doesn’t ignite at the right time or fails to ignite at all. This results in rough running and reduced engine performance.

Common causes of engine misfires

• Faulty spark plugs or ignition coils
• Worn distributor cap or rotor (in older cars)
• Clogged or leaking fuel injectors
• Weak fuel pump or clogged fuel filter
• Vacuum leaks or intake air leaks
• Faulty sensors (oxygen sensor, MAF, crankshaft position sensor)
• Low compression due to worn valves, piston rings, or head gasket failure

Why do you need to fix this problem quickly?

Driving with a misfiring engine increases fuel consumption, reduces power, and can damage the catalytic converter from unburned fuel entering the exhaust. Long-term misfires can also cause major engine wear.

How do you know when to get it checked?

You should book an inspection if:

• The engine shakes or vibrates, especially at idle
• You hear popping or sputtering noises from the exhaust
• Acceleration feels weak or uneven
• The Check Engine Light is flashing or illuminated
• You notice increased fuel consumption or exhaust smoke

What happens during an assessment?

A mechanic will:

1. Scan the ECU for misfire codes (e.g. P0300, P0301, etc.)
2. Inspect and test spark plugs, ignition coils, and wiring
3. Check fuel injectors, fuel pressure, and fuel filter
4. Inspect for vacuum or intake air leaks
5. Test engine compression and cylinder condition
6. Check oxygen and airflow sensors for faults

How much does it cost to fix?

Replacing spark plugs or coils typically costs $150–$400. Fuel injector or sensor repairs range from $300–$800. More serious issues like compression loss or head gasket repairs can cost $1,500–$3,500+.

Is it unsafe to drive with an engine misfire?

Yes. Misfires reduce power, increase emissions, and can cause severe damage to the catalytic converter and engine if ignored. A flashing Check Engine Light means the car should not be driven until repaired.