Quick Diagnosis Guide
Meaning: Code P0304 indicates that the vehicle's onboard computer (ECU) has registered a fault in the powertrain (p) circuits.
Can I still drive? No. Avoid driving to prevent exhaust melting.
What does the P0304 code mean?
Diagnostic Trouble Code (DTC) P0304 stands for Cylinder 4 Misfire Detected. This is a generic OBD-II trouble code indicating that the ECU has detected system performance parameters that fall outside normal calibrated tolerances.
When this code is logged, the ECU illuminates the dashboard check engine light and triggers a freeze frame record of engine sensor values to help diagnose the issue.
Common Symptoms of Code P0304
Depending on the vehicle make and driving conditions, you may observe the following symptoms:
- Engine sputter
- Poor acceleration
- Rough running
What causes the P0304 fault code?
Root causes for a P0304 code typically include:
- Potential Cause 1: Ignition coil failure on Cylinder 4
- Potential Cause 2: Spark plug fouled on Cylinder 4
- Potential Cause 3: Wiring connector loose
Repair Database Status
No verified vehicle-specific workshop fix is currently logged in our mobile mechanic database for this code. Refer to the diagnostic checklist below to isolate the fault.
Step-by-Step Diagnostic & Inspection Checklist
To inspect and troubleshoot a P0304 code, mechanics follow these validation steps:
- Step 1: Confirm code P0304 in OBDAssistant.
- Step 2: Inspect spark plug condition on cylinder 4.
Estimated Repair Cost Band
$60 - $200.
Note: Repair estimates vary based on vehicle make, model, local labor rates, and whether you require a full parts replacement.
Related Trouble Codes
If your scan tool registers other codes, check out these related guides:
Frequently Asked Questions
Usually a bad spark plug, failing ignition coil, or localized vacuum leak near Cylinder 4.