The purpose of this paper is to discuss the complex problem area of inspection and maintenance and to show a possible way out of this problem.
The main difficulty of inspection and maintenance results from the high variability of exhaust emission values. Therefore only cars with very high emissions far beyond the production distribution curve, so-called outliers, can be identified in an emission test.
For the detection of such outliers a new measurement procedure for catalyst equipped passenger cars is presented. The basic idea is to determine the conversion rate of the catalytic system with regard to the exhaust emission components HC, CO and NOX using the new test procedure (“component check/catalyst”) which is suitable also for routine checks. It is important to check the catalytic system under dynamic engine conditions. On the other hand the procedure should operate without a chassis dynamometer - because of cost reasons. These conditions can be fulfilled by the “component check/catalyst” test proposed by Volkswagen.