A method of measuring temperature of a catalytic converter in a motor vehicle includes the step of determining a first oxygen sensing mechanism output, determining if it is time to determine a second oxygen sensing mechanism output, and determining the second oxygen sensing mechanism output if it is time to determine the second oxygen sensing mechanism output. The method also includes the step of determining a change in oxygen sensing mechanism output by taking a difference between the first oxygen sensing mechanism output and the second oxygen sensing mechanism output. The method further includes the step of finding a catalytic converter temperature in a look-up table using the change in oxygen sensing mechanism output, and using the catalytic converter temperature as needed by an electronic control mechanism to operate an engine of the motor vehicle.