Cylinder 4 Misfire Detected
The engine control module detected misfires in cylinder 4, meaning the fuel-air mixture is not igniting properly in that cylinder. This causes incomplete combustion and can damage the catalytic converter if left unrepaired.
What You Might Notice
- Engine hesitation or stumbling during acceleration
- Rough idle or vibration at stop lights
- Difficulty starting the engine
- Reduced fuel economy
- Engine check light illuminated
Most Common Causes
- 1
Faulty spark plug or wire
A worn or fouled spark plug, or damaged spark plug wire, prevents proper ignition in cylinder 4. Replace spark plugs and inspect wires for cracks or wear.
- 2
Faulty ignition coil pack
A defective coil pack dedicated to cylinder 4 fails to generate sufficient voltage to fire the spark plug. Individual coil packs can fail independently.
- 3
Fuel injector malfunction
The fuel injector for cylinder 4 may be clogged, leaking, or electrically faulty, preventing proper fuel delivery. This disrupts the fuel-air ratio needed for combustion.
- 4
Low compression or burned exhaust valve
Internal engine damage such as worn piston rings or a burned valve in cylinder 4 prevents proper compression and combustion. This requires more extensive engine work.
How to Diagnose It
- 1
Check Faulty spark plug or wire — A worn or fouled spark plug, or damaged spark plug wire, prevents proper ignition in cylinder 4. Replace spark plugs and inspect wires for cracks or wear.
- 2
Check Faulty ignition coil pack — A defective coil pack dedicated to cylinder 4 fails to generate sufficient voltage to fire the spark plug. Individual coil packs can fail independently.
- 3
Check Fuel injector malfunction — The fuel injector for cylinder 4 may be clogged, leaking, or electrically faulty, preventing proper fuel delivery. This disrupts the fuel-air ratio needed for combustion.
- 4
Check Low compression or burned exhaust valve — Internal engine damage such as worn piston rings or a burned valve in cylinder 4 prevents proper compression and combustion. This requires more extensive engine work.
How to Fix It
- 1
Replace spark plug and inspect wire
Remove and inspect the spark plug for cylinder 4; replace if worn, fouled, or gapped incorrectly. Check the spark plug wire for cracks, splits, or corrosion and replace if damaged.
- 2
Test and replace ignition coil pack
Using a multimeter or coil pack tester, verify the coil pack for cylinder 4 is functioning. If faulty, replace the coil pack assembly.
- 3
Clean or replace fuel injector
Have the fuel injector for cylinder 4 professionally cleaned using fuel injector cleaning service, or replace it if cleaning does not resolve the misfire.
- 4
Perform compression test and inspect valve train
If previous fixes fail, perform an engine compression test on cylinder 4 to check for internal damage. A low reading indicates burned valves or worn pistons requiring engine repair.
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