Check Valve

A check valve should be inspected whenever the hose is disconnected or whenever check valve failure is suspected. An AIR pump that had become inoperative and had shown indications of having exhaust gases in the outlet port would indicate check valve failure.
1. Remove the check valve from the vehicle. Refer to Secondary Air Injection (AIR) Check Valve/Pipe Replacement - Bank 1 or Secondary Air Injection (AIR) Check Valve/Pipe Replacement - Bank 2
2. Install a vacuum pump to the nipple side of the check valve, AIR pump side.
3. Pump the vacuum pump to 10 inches Hg and observe the gauge.
4. Replace the check valve if the vacuum bleeds down to zero within 5 seconds.