What does trouble code PO502 mean on a 2002 Volvo V70?

The trouble code P0502 on a 2002 Volvo V70 indicates a problem with the vehicle speed sensor (VSS) circuit, specifically that the input signal is lower than expected. This can result from a faulty speed sensor, damaged wiring, or a poor connection in the circuit. As a consequence, issues such as erratic speedometer readings or transmission shifting problems may occur. It's advisable to inspect the sensor and associated wiring for faults to resolve the issue.