Engine exhaust heat flux control system and method

A method of control of an engine 14 with a turbocharger 18 having a wastegate 36, a throttle valve 38 and an aftertreatment device(s) 30, 32, 34, such as DOC, DPF or SCR, and a controller (100, figure 2), configured to receive a plurality of engine parameters. The controller is used to process whether thermal management of the aftertreatment device(s) is required by determining a target condition (206, figure 4) for the aftertreatment device from an engine parameter(s), wherein the target condition includes a target temperature for the aftertreatment device and determining whether thermal management will be performed according to heat flux control or temperature control from the engine parameter(s) and the target conditions. Control of the throttle valve and wastegate is applied accordingly. The controller may include a stored map of the wastegate control parameters as a function of engine parameters. The engine perameter(s) may include engine speed and fuel usage. A control system, a combustion engine and a non-transient computer readable medium is also claimed.