What does OBD2 code P0304 mean?
The engine control module (ECM) or powertrain control module (PCM) sets code P0304 when it registers that the Cylinder 4 Misfire Detected performance has fallen below the manufacturer's required baseline. This triggers your vehicle's malfunction indicator lamp (MIL), commonly known as the Check Engine Light.
Is It Safe to Drive with Code P0304?
No. Avoid driving to prevent exhaust melting.
Symptoms of OBD2 Code P0304
Depending on your car model, symptoms for P0304 may vary. The most typical symptoms include:
- Engine sputter
- Poor acceleration
- Rough running
What Causes Code P0304?
A variety of physical faults can trigger the P0304 code. Here are the most frequent culprits:
- Ignition coil failure on Cylinder 4
- Spark plug fouled on Cylinder 4
- Wiring connector loose
Step-by-Step Diagnostic Routine
Before replacing any expensive components, run through these standardized troubleshooting steps:
- Confirm code P0304 in OBDAssistant.
- Inspect spark plug condition on cylinder 4.
Expected Repair Costs for P0304
$60 - $200.
Save on Diagnosis with OBDAssistant
Shows diagnostic telemetry to confirm if Cylinder 4 is failing continuously or intermittently.
Frequently Asked Questions
Usually a bad spark plug, failing ignition coil, or localized vacuum leak near Cylinder 4.