The air pump check valve is a one way valve that allows air from the air pump to enter the exhaust system. More importantly, it prevents hot exhaust gases from entering the Secondary Air Injection System.
How does the air pump check valve work?
The check valve can be vacuum operated or strictly mechanical in nature. A mechanical valve will simply let pressurized airflow in only one direction. A vacuum operated check valve will use a controlled vacuum source to open and close the valve at the appropriate time.
When the air pump check valve is malfunctioning, the vehicle may perform normally, but may fail an emissions inspection and get poor gas mileage. The Check Engine Light may illuminate with a code set for the secondary air injection system.
What are the symptoms related to a bad air pump check valve?
When the air pump check valve is malfunctioning, the vehicle may perform normally, but may fail an emissions inspection and get poor gas mileage. The Check Engine Light may illuminate with a code set for the secondary air injection system. A melted Secondary Air Injection rubber hose could be caused by a leaking check valve.
Can I drive with an air pump check valve problem?
A vehicle should not be driven if the check valve is allowing hot exhaust gasses into the rubber hoses of the Secondary Air Injection system as this could result in damage to the hoses and other components. If the valve is simply restricted and not allowing flow in either direction, it should be OK to temporarily drive the vehicle.
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How often do air pump check valves need to be replaced?
Whether or not a Secondary Air System Check Valve(s) will fail can vary greatly for different makes and models. Geographic locations where road salt is used may see more failures because rust can greatly shorten the life the check valve(s).
How are air pump check valve issues diagnosed?
Most commonly an illuminated check engine light would lead to retrieval of a fault code indicating a problem with a Secondary Air System check valve. A suspect valve would then be tested for proper operation, unrestricted flow in one direction and no flow in the other. Heat damaged Secondary Air Injection hoses and/or components would also lead to inspection of the check valve(s) for proper operation.
An air injection system trouble code isn't always triggered by a defective air pump check valve. It can also be triggered by a restricted passage or air pipe, a defective air pump, an air pump relay failure, or a wiring problem.
How is an air pump check valve replaced?
A Secondary Air System Check Valve will either screw directly onto a pipe connected to the exhaust system or bolt onto a metal flange that is part of the exhaust system. On some models, various components my need to be removed to gain access to the valve. A bit of penetrating oil on the mounting threads or bolts can greatly aid in removal of the old valve.
When replacing the air pump check valve, be sure to perform a thorough inspection of the air injection components and passages. Always use factory parts and check for any needed software updates for the power train control module (PCM).
BMW 328xi Air Injection System Check Valve Replacement Cost by Year
The average cost for a BMW 328xi Air Injection System Check Valve Replacement is between $258 and $309 but can vary from car to car.
