An electronic device may include protection circuitry coupled to a connector port. The connector port may be a reversible connector port that receives a mating reversible connector plug with either first or second orientations. The connector port may include contacts for receiving and/or transmitting signals during communications between the electronic device and the accessory device. The protection circuitry may monitor signals received at the contacts to determine whether transient or permanent connection faults exist. In response to determining that a connection fault exists at any of the contacts, the protection circuitry may electrically disconnect the faulty contacts from processing circuitry in the electronic device.