Patent ID: 7647765

Claim:
A system for an engine having an intake system and an exhaust system, comprising: an airflow sensor coupled to the intake system; a throttle plate coupled to the intake system downstream of said airflow sensors; an air pump having at least an inlet side and an outlet side; an exhaust gas oxygen sensor coupled to the exhaust system; a first, upstream, duct having at least a first end coupled to said inlet of said pump and a second end coupled to the intake system downstream of said airflow sensor and upstream of said throttle plate; a second, downstream, duct having at least a first end coupled to said outlet of said pump and a second end coupled to the exhaust system, said second end of said second duct being coupled to multiple locations of the exhaust system upstream of said exhaust gas oxygen sensor; and a controller coupled to the engine, said controller, during operation, identifying whether degradation has occurred to at least one of said first duct and said second duct, distinguishing between degradation of said first duct and said second duct, and providing an indication of said identified, distinguished, degradation.