A multiphase voltage regulator includes a plurality of power stages, a plurality of current sense circuits, a controller and a current sense interface running between the controller and one or more of the current sense circuits. The current sense interface includes a separate line for each current sense circuit coupled to the current sense interface and which is configured to support single-ended or differential current sense. The regulator also includes a plurality of pullup circuits, each of which is connected to one of the current sense interface lines and has a higher impedance than the line to which it is connected. A fault detection circuit of the controller determines if an individual one of the current sense interface lines has an open fault, based on the pullup circuit connected to the line with the open fault pulling up the voltage on the line by more than a predetermined amount.