Abstract: A method and apparatus for detecting a damaged encoder strip are described. An encoder strip is scanned in two separate operations at two separate times, a first operation and a second operation. The number of markings sensed in each separate operation is counted.. A circuit compares the count of markings in each separate operation. If the count differs between the two operations, the circuit determines that the encoder strip is damaged, and the circuit develops a signal indicating this damage. In an embodiment, the first operation is performed during a calibration, and the second operation is performed during a power-on, or upon operator command.