The window regulator is the mechanism which raises and lowers your door window, with the use of the electrical window switch. Faulty windows could be caused by a faulty control switch, a break in the mechanism or a fault in the motor. Should you experience a faulty window in your Volvo S40, it is advisable to identify which of these are causing your issue. In general there may be one of two types of window regulators fitted to your Volvo S40. Higher spec vehicles may have a one touch system when pressing the switch, whereas the other type necessitates keeping your finger on the switch for it to continue putting the window up or down.

The one touch system (also known as the comfort system) will have a more complicated wiring structure with a connecting block of approximately 6 wires, as opposed to 2. For this reason the two are not interchangeable, therefore it is important to identify the type on your Volvo S40 before you order.