An improved system and method for testing a sensor of a portable electronic device based on expected sensor data and not timing information. The system and method for testing a sensor of a portable electronic device retrieves sensed data from the portable electronic device (i.e. device under test) after the device has traversed a series of test areas or zones. The sensed data is compared against a set of expected sensor data patterns to determine which components of the sensed data correspond to each test area or zone. The sensor of the portable electronic device may be tested based on an association of the test areas or zones with segments of the sensed data.