DPF failure detection method and DPF failure detection device

A diesel particulate filter (referred to as “DPF” hereinafter) failure detection device for detecting a failure in a DPF that is arranged in an exhaust pipe guiding exhaust gas from an internal combustion engine to the atmosphere,

• the DPF failure detection device comprising:
• a theoretical deposited amount calculator that calculates a deposited amount (referred to as “theoretical deposited amount” hereinafter) of a particulate matter (referred to as “PM” hereinafter) on the DPF from an operating state of the internal combustion engine;
• an electrical capacitance type PM sensor that is configured by two electrodes disposed in the DPF;
• an actual deposited amount measuring unit that measures a deposited amount referred to as “actual deposited amount” hereinafter) of the PM on the DPF (based on an electrical capacitance of the electrical capacitance type PM sensor;
• and
• a failure diagnosis unit that determines that the DPF has a failure, when a divergence of the actual deposited amount from the theoretical deposited amount exceeds an allowable limit, the actual deposited amount being measured by the actual deposited amount measuring unit while the theoretical deposited amount being calculated by the theoretical deposited amount calculator.