What Is a Secondary Air Injection System Malfunction?

A secondary air injection system malfunction occurs when outside water collects inside of the air pump of a vehicle's exhaust system, disabling the pump's ability to pass outside air through the exhaust system. This outside water may then freeze, causing the air pump to freeze and malfunction, explains OBD-Codes.com.

The air pump is used to lower the emission levels of a car by pumping outside air through a one-way valve into the vehicle's exhaust system. A secondary air injection system malfunction occurs when water enters the car's exhaust. This water collects and in many cases becomes frozen to the air pump. When the Powertrain Control Module, or PCM, signals the pump to start, because of the ice, the circuit "pops" the fuse.

In addition to a fuse "popping," some symptoms of this malfunction are hesitation on acceleration and noise from the air pump itself. When replacing the air pump, replace the one-way check valve as well. Test and clean both the air pump and the one-way check valve. Also replace the air pump inlet hose, as this may have collected water and unseen debris in it. Finally, replace the air pump fuse. This is located under the hood of the vehicle.