Patent ID: 6668631
Filing Date: 2003-12-30
Classification: F01N,Y02T

Abstract:
A method of checking the operation of a catalyst arranged in an exhaust gas pipe of an internal-combustion engine, a sensor being arranged behind the catalyst and detecting exhaust gas values, the method comprising the acts of:determining similar operating conditions of the internal-combustion engine via detected operating parameters; forming a statistically backed total average exhaust gas value from a defined number of exhaust gas values during a particular similar operating condition; comparing said statistically backed total average exhaust gas value with a maximally permissible exhaust gas value stored in a memory for the particular similar operating condition; recognizing the catalyst is defective when the statistically backed total average exhaust gas value exceeds the permissible exhaust gas value; checking a result of the comparison of the statistically backed total average exhaust gas value with the permissible exhaust gas value stored in the memory via a second sensor arranged in front of the catalyst and via an analysis of a conversion rate with respect to plausibility of the statistically backed total average exhaust gas value.