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The code P0410 is lack of air flow with the secondary air pump on,suspect cause is leak in air hose or hose disconnected.
P0491 is the air system detected that there was insufficent mass air flow change during pump swithching on and off.
possible causes: no flow from secondary air pump, secondary air bypass solenoid leaking or stuck open,air diverter valve leaking,blocked, or stuck open.
secondary vacuum hose leaking
secondary air hose restricted
Here is a pic of the system
During self test the pump will be energized.Make sure you have vacuum to it then disconnect the outlet hose and see if you get air flow
Then work your way back to the air valve
I would suggest to put your hand first on the air diverter valve, see the black on left side of pic. You should feel it cycle on during key on engine running self test.If it doesn't then hook a test light in between the connector and see if it lights during self test.This should pin point the vlave.
You can disconnect the hose on the air pump and you should feel it pumping air during key on engine running self test
I aid diveter valve but the solenoid that the vacuum line hooks to
did that make sense?