P0304: Cylinder 4 Misfire Detected

What P0304 usually means

P0304 narrows the misfire pattern to cylinder 4. It often comes down to the same categories as other single-cylinder codes: spark, fuel, air at that runner, or mechanical condition.

Start here before chasing parts

• Scan first: save freeze-frame and pending codes before clearing anything.
• Confirm the complaint: compare the stored code with current drivability symptoms.
• Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
• Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.

Suggested workflow

1. Check plug and coil
2. Inspect injector pulse
3. Compression/leak-down if unresolved

Common mistakes

• Clearing the code and continuing to drive without confirming whether the misfire is active.

Practical fix guidance

• Repair the root cause and verify that the catalyst was not damaged by prolonged misfire.

Affected brands in this MVP

• Chevrolet

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.