95 C280 - 8 Year/80,000 mile emissions warranty

I recently had to replace the air mass meter(sensor) and coolant temperature switch on my 1995 C280 with 69,000 miles. These parts were determined to require replacement after the check engine light came on. Since these parts directly effect the engine emissions, I felt that they should be covered by the 8 year/80,000 mile emissions warranty. The Mercedes dealer, however, indicated that these parts are not covered by the emissions warranty and would need to be replaced at my expense ($637. 53). I still feel that these parts directly effect vehicle emissions and therefore should be covered. Who's correct?