Malfunction Threshold

The fluctuation of the brake booster pressure sensor value is less than 1 kPa (0.4 inHg, 9 mmHg) while repeating the sequence of "the vehicle speed is 19 mph (30 km/h) → 0 mph (0 km/h) → 19 mph (30 km/h)" for five times (it is a situation that the brake booster pressure value should drop due to the braking operations or should increase/decrease due to the negative pressure being applied from the supply source).