Vehicle diagnostic device

A vehicle diagnostic device that is configured to diagnose a vehicle by using a pressure sensor, the vehicle including an engine in which a filter is attached to an exhaust pipe, the filter collecting particulate matter, a pressure piping that branches from an upstream side of the filter of the exhaust pipe, bypasses the filter, and connects to a downstream side of the filter, and the pressure sensor that is attached to the pressure piping and detects a differential pressure between the upstream side and the downstream side of the filter, the vehicle diagnostic device comprising:

• a processor configured to:
• prohibit diagnosing the vehicle using the pressure sensor when a first condition is satisfied;
• and
• when a second condition is satisfied, allow diagnosing the vehicle using the pressure sensor, the second condition including (i) a condition where freezing of water in the pressure piping is estimated, and (ii) a condition where an integrated value of time traveled at a predetermined vehicle speed or less exceeds a time determination value after warming up of the exhaust pipe is finished.