Meaning
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.
DTC code page
P0304: Cylinder 4 Misfire Detected
Quick answer: Misfire was primarily detected on cylinder 4.
Drivers also search this fault as cylinder 4 misfire, misfire cylinder 4, number 4 cylinder misfire.
Severity: high Family: powertrain Related paths: 5
Fast triage
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.
Initial checks
What to check first
- Check plug and coil condition on cylinder 4 before moving to deeper testing.
Driving risk
Can you keep driving?
Do not treat an active P0304 as harmless. Continued driving can overheat the converter.
High urgency: If symptoms are active, reduce driving and diagnose quickly before secondary damage builds.
Symptoms
Common symptoms
- Engine Misfire
- rough engine
- shaking under load
- check engine flashing
Likely causes
Common causes behind this code
- Ignition coil issue
- Injector issue
- Mechanical issue
Cause phrases often tied to this code: ignition coil issue, injector issue, mechanical issue.
Diagnostic order
Suggested workflow
- Check plug and coil
- Inspect injector pulse
- Compression/leak-down if unresolved
Avoid guesswork
Common mistakes
- Clearing the code and continuing to drive without confirming whether the misfire is active.
Repair path
Practical fix guidance
- Repair the root cause and verify that the catalyst was not damaged by prolonged misfire.
Vehicle context
Affected brands in this MVP
Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.
Aliases and common searches
English phrases tied to P0304
Useful when the driver knows the wording but not the exact DTC yet.
- cylinder 4 misfire
- misfire cylinder 4
- number 4 cylinder misfire
Related search intent
Queries this page can answer naturally
- P0304 code meaning
- what does P0304 mean
- cylinder 4 not firing
FAQ
Quick questions about P0304
Can I clear P0304 and keep driving?
Clearing the code does not fix the misfire and may risk catalyst damage if the fault is active.