CONTROLLER AND CONTROL METHOD FOR VEHICLE

A controller includes a soak timer, a nonvolatile memory, and a determining section. The determining section is configured to perform a rationality check on a condition that a performance condition is met. The determining section is also configured to make the performance condition strict when an obtained index value of a vehicle outside temperature, that is obtained when an elapsed amount of time reaches a specified amount of time, and the determining section is activated, is higher than a stored index value of the vehicle outside temperature stored in the nonvolatile memory.