P0304 - Cylinder 4 Misfire Detected
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0304 signifies that the Engine Control Module (ECM) has detected multiple misfire events on cylinder number 4. The ECM monitors the crankshaft position (CKP) sensor to detect minute fluctuations in rotational speed during each cylinder's power stroke. If a specific cylinder contributes less torque than expected, a misfire is recorded. Chronic misfires can lead to catalytic converter damage due to unburned fuel entering the exhaust stream.
Possible Causes
Faulty spark plug or ignition coil (COP)
Faulty fuel injector (clogged or electrical failure)
Intake manifold vacuum leak near cylinder 4
Low engine compression (burnt valves or piston ring issues)
Wiring harness issues or corroded connectors
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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