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IgnitionSeverity High: diagnose before driving on

P0307Cylinder 7 Misfire Detected

What it means

The ECU has seen cylinder 7 misfire: the crankshaft slows down each time that cylinder should fire. A misfire that is bad enough to flash the check engine light can overheat and damage the catalytic converter.

Symptoms

  • Engine shakes or runs rough
  • Loss of power, especially under load
  • Flashing check engine light under load

Common causes

  • Ignition coil or spark plug on cylinder 7
  • Injector on cylinder 7 (clogged, leaking or not firing)
  • Low compression on cylinder 7
  • Vacuum leak close to that cylinder

What to check first

  1. Swap the coil (and plug) with another cylinder and see whether the misfire follows
  2. Check the injector (resistance, scope, balance test)
  3. Run a compression test on that cylinder
Can I drive with P0307? Not recommended. P0307 can lead to stalling, limp mode or engine damage; diagnose it before driving further.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

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P0307: questions and answers

What does P0307 mean?

P0307: Cylinder 7 Misfire Detected. The ECU has seen cylinder 7 misfire: the crankshaft slows down each time that cylinder should fire. A misfire that is bad enough to flash the check engine light can overheat and damage the catalytic converter.

What are the symptoms of P0307?

Engine shakes or runs rough. Loss of power, especially under load. Flashing check engine light under load.

What causes P0307?

Ignition coil or spark plug on cylinder 7. Injector on cylinder 7 (clogged, leaking or not firing). Low compression on cylinder 7. Vacuum leak close to that cylinder.

How do you diagnose P0307?

1. Swap the coil (and plug) with another cylinder and see whether the misfire follows 2. Check the injector (resistance, scope, balance test) 3. Run a compression test on that cylinder

Can I drive with P0307?

Not recommended. P0307 can lead to stalling, limp mode or engine damage; diagnose it before driving further.