START-UP METHOD AND APPARATUS FOR CAM ANGLE SENSOR ERROR OF MILD HYBRID SYSTEM

A start-up method of a mild hybrid system determines whether start-up is attempted through an MHSG in accordance with a request for start-up from a driver, compares an engine rpm at the end of cranking with a reference rpm in start-up using the MHSG, determines whether an engine rpm immediately after start-up follows an idle target rpm when the engine rpm at the end of cranking exceeds the reference rpm, checks whether there is an error in a cam angle sensor when poor following in which the engine rpm immediately after start-up does not follow the idle target rpm is generated, forcibly changes an engine state into cranking when the cam angle sensor has an error, and executes an existing backup crank logic that decreases a target rpm of the MHSG and finds out a fuel injection time while performing test injection using a signal from an crank angle sensor.