Strategy for enabling intake air heater to clean up white smoke during warm engine re-start in cold weather

A method for attenuating white smoke in exhaust gas entering atmosphere from a compression ignition engine housed within an engine compartment of a motor vehicle by enabling an intake air heater to heat combustion air passing through an air intake to the engine upon engine starting and during a subsequent period of initial engine running, the method comprising:

• evaluating temperature indicated by a sensor disposed at a location in the air intake;
• and if, upon engine starting, the evaluated temperature exceeds a reference temperature that demarcates a cold engine from a warm engine, enabling the heater to heat combustion air passing through the air intake for a length of initial engine running time that is subsequent to engine starting and that is a function of the evaluated temperature.