On my 2000 ford mustang why does my air pump (smog pump) only blow air for 5 seconds after start up? Is that normal?

I have p0411 secondary air injection system insufficient flow detected. I've checked the hose that comes out from the pump, it's blowing air but I believe it should blow air for much longer than 5 seconds on start up.

Look here - https://www.obd-codes.com/p0411