Disclosed is an elevator control system configured to control movement of an elevator car (12) along an elevator hoistway (26) between a starting position and a destination position (L2), the control system comprising a car holding position monitoring unit configured to monitor whether the elevator car (12) has moved upwards or downwards in the hoistway (26) during a holding period (68) where the car (12) was intended to remain stationary at the destination position (L2). The car holding position monitoring unit is configured to: Receive a first trigger signal (62) from a first car position reference system (40); upon receipt of the first trigger signal, receive signals from a further car position reference system to detect a first indicator (66) indicative of a travel distance (X2) between the position of the elevator car (12) in the hoistway (26) when receiving the first trigger signal (62) and the position of the elevator car (12) in the hoistway (26) when stopping at the destination position (L2); upon receipt of a further service call for the elevator car (12), receive further signals from the further car position reference system and receive a second trigger signal (70A) from the first car position reference system (40) to detect a second indicator (74A) indicative of a travel distance between the position of the elevator car (12) in the hoistway (26) at the end of the holding period (68) and the position of the elevator car (12) in the hoistway (26) when the elevator car (12) receives the second trigger signal (72A) from the first car position reference system (40); and detect whether the elevator car (12) has moved during the holding period (68) based on a comparison of the first indicator (66) and the second indicator (74A).