What causes white smoke from exhaust on natural gas engine?

White smoke from the exhaust of a natural gas engine typically indicates incomplete combustion or the presence of water vapor. This can occur due to issues such as an improper air-fuel mixture, coolant leaking into the combustion chamber, or low combustion temperatures. Additionally, condensation of water vapor in the exhaust system can also lead to white smoke, especially during startup or in cooler temperatures. Proper maintenance and tuning of the engine are essential to mitigate this issue.