METHOD FOR JUDGING ACTIVITY OF SENSOR AND FOR CONTROLLING MEASUREMENT GAS

摘要

PROBLEM TO BE SOLVED: To provide a control method which can start a control in a short time with the use of a plurality of sensors. SOLUTION: An activity of each of a reductive gas sensor S1 and an oxidative gas sensor S2 is judged on the basis of the fact that a resistance value turns to increase from a decrease after heating is started (S10). When the reductive gas sensor S1 becomes active (S12: Yes), switching between circulation inside vehicle and circulation outside vehicle is started on the basis of a signal from the reductive gas sensor S1. When the oxidative gas sensor S2 becomes active (S22: Yes), the switching is started on the basis of a signal from the oxidative gas sensor S2 (S26). The switching can be started in a short time with the use of the oxidative gas sensor and the reductive gas sensor of different times to be active.