Detection device for internal combustion engine

A detection device for an internal combustion engine which is applied to the internal combustion engine including a sensor equipped with a cover for covering a temperature varying member, which is provided in an exhaust system, and whose temperature varies due to gas flow in the exhaust system, comprising:

• a temperature correlation value detection unit which detects a correlation value which correlates with the temperature of the temperature varying member;
• and
• a variation calculating unit which calculates a variation of the correlation value, in a time period when the gas flow arises, detected by the temperature correlation value detection unit,
• wherein an exhaust temperature sensor which detects temperature of the gas is provided on a streamline which is approximately same as the streamline where the temperature varying member is provided in the exhaust system, and
• wherein the variation calculating unit calculates a rate of the variation of the correlation value to a variation of an exhaust temperature detected by the exhaust temperature sensor and detects clogging or cracking in the cover based on the rate of the variation.