Intake Air Heater: Description and Operation

The Fuel Evaporation Heater (EFE) switch, is mounted upside down at the rear of the engine on the bottom of the intake manifold. The purpose of the switch is to control a relay and heater element in the early fuel evaporation system (EFE) based on engine temperature The normally closed switch will activate the relay and heater at low engine temperature and will open at the specified calibration temperature of the switch. This will open the control relay shutting off the EFE heater after engine warm-up.