Abstract: A fuel injection control system in an automobile engine comprising an intake system for the supply of air towards the engine and including an air flow sensor, an exhaust system for the discharge of exhaust gases, a supercharger in the intake system for compressing the air flowing towards the engine, and a secondary air supply passage extending between the intake and exhaust systems for the introducing of a portion of the compressed air into the exhaust system and including a secondary air flow sensor. During a normal operating condition, fuel is injected into the engine in a quantity dependent on the difference between the air flow detected by the air flow sensor and the secondary air flow detected by the secondary air flow sensor, but in the event of trouble occurring in the secondary air flow sensor, the fuel is injected in a quantity dependent on the air flow detected by the air flow sensor.