Abstract
Investigation show there are many important influence factors can affect the light-off temperature (LOT in brief) testing results of catalytic converters. Contrast tests results show that different sample sizes and sample outside temperature result in different light off process. Exorbitant temperature of the gas heater and metal tube by which the exhaust gases pass through could arouse chemical reaction before the converter sample. Concentration of exhaust gases also can take effects on LOT testing results.