Engine emits white smoke, especially on cold start; rough running until warm.

Safety: Avoid prolonged idling with heavy white smoke; unburned fuel can damage the DPF (if equipped).

• Check coolant temperature: Ensure the engine reaches normal operating temperature. A stuck-open thermostat can keep cylinders too cool.
• Use preheat (if equipped): Verify that intake air heaters or glow plugs (if fitted) are functioning. Repair or replace failed preheat components.
• Fuel quality: Drain water and contaminants from the fuel system. Use clean, season-appropriate diesel fuel.
• Further diagnosis: Persistent white smoke may require compression testing and injector bench testing by a qualified technician.