Electronic engine controls are being developed for heavy duty diesel truck engines to improve performance and fuel consumption at the current and future gaseous emission requirements. Caterpillar is developing a programmable electronic engine control (PEEC) for the 3406 Truck Engine. The in-line 6 cylinder engine currently covers the power range from 255 to 400 hp (190 to 298 kW). The PEEC system has been designed specifically to work with the new fuel system recently introduced on the 3406B Engine (1)*. This paper discusses the design, functions and performance aspects of the 3406 PEEC Engine.