Patent ID: 7890283

Claim:
A malfunction detection system which detects a malfunction in a sensor, said malfunction detection system comprising: a sensor including a first terminal, and which outputs a sensor output current that varies a voltage level of the first terminal; a current outputter configured to vary the voltage level of the first terminal by outputting a current for judging to said sensor via the first terminal; a judger configured to judge that said sensor is malfunctioning when the current for judging causes the voltage level of the first terminal to be equal to or higher than a threshold in a period different from a first period where the sensor output current causes the voltage level of the first terminal to be equal to or higher than the threshold; and a period controller configured to set a second period and a third period in such a manner that at least one of the second period and the third period is different from the first period, wherein said current outputter is configured to output the current for judging to said sensor via the first terminal in the second period and the third period that are set by said period controller, said judger is configured to judge that the sensor is malfunctioning when the voltage level of the first terminal is equal to or higher than the threshold in both of the second period and the third period, and said period controller is configured to set a checking period for checking for the malfunction of the sensor, the checking period including the second period and the third period and being set in such a manner that a period between a starting point of the second period and a starting point of the third period is longer than the first period.