Home >> Audi >> 2000 >> TT Base, 1.8 S >> Repair and Diagnosis >> Engine Mechanical >> Blowers, Superchargers & Turbochargers >> 1.8L - Turbo Engine Mechanical, Engine Code(S): Amu, BEA >> 26 Exhaust system, Emission controls >> Secondary Air Injection (AIR) system, checking >> Secondary Air Injection (AIR) solenoid valve -N112-, checking >> Checking internal resistance