P0303

What does P0303 mean?

P-code P0303 means "Cylinder 2 Misfire Detected". It is a generic OBD-II diagnostic trouble code (DTC) in the ignition system. A fault has been detected in the cylinder 2 misfire detected — the control module has logged this condition during self-diagnostics. This code can be monitored, but service is recommended to prevent escalation. This code applies to OBD-II compliant electric and hybrid vehicles.

Possible Causes

• Faulty or failed component in the ignition system
• Damaged or corroded wiring and electrical connectors
• Control module software error or firmware fault
• Poor or missing ground connection at the affected module

Recommended Actions

1. 1 Note the alert and schedule a diagnostic appointment when convenient
2. 2 Scan for all DTCs with an OBD-II scanner — note any related codes stored alongside P0303
3. 3 Inspect the ignition system component and its wiring for visible damage
4. 4 Check for water intrusion in connector areas and clean contacts if corroded
5. 5 Clear the DTC, road-test the vehicle, and re-scan to confirm whether the fault returns
6. 6 If the fault persists after inspection and clearing, consult an EV-certified technician for component replacement

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