Diagnosing a supercharger off of generated pressure

A diagnosis device comprising:

• a communication unit configured to communicate with a plurality of vehicles each including an internal combustion engine and a supercharger;
• an acquisition unit configured to acquire, through the communication unit from each of the plurality of vehicles, cumulative data for each parameter related to stress acting on the supercharger configured to supercharge intake air to the internal combustion engine and a supercharging pressure of the supercharger;
• a damage degree identification unit configured to identify a degree of damage to the supercharger of each of the plurality of vehicles based on the acquired cumulative data;
• a relationship identification unit configured to identify a relational expression indicating a relationship between the identified degree of damage and the supercharging pressure;
• a supercharging pressure acquisition unit configured to acquire the supercharging pressure of the supercharger through the communication unit from a target vehicle to be diagnosed which is included in the plurality of vehicles;
• and
• an estimation unit configured to estimate a degree of damage to the supercharger of the target vehicle based on the supercharging pressure of the target vehicle acquired by the supercharging pressure acquisition unit and the relational expression identified by the relationship identification unit,
• wherein the cumulative data indicates a frequency of each parameter including at least one of use in an operation in which an engine oil is consumed in a large amount and use in a state in which the intake air is at a high temperature.