Secondary air intake code

[Fuzzuki]

My car keeps showing a code for the secondary air intake.
I know it means that the blower motor is not functioning.
But I do hear it working most times I start the car.

After I clear the code, it is fine for weeks, but then when I come off the highway, the secondary air fan will not be functioning and the idle dips and stumbles and recovers, then the code comes back showing check engine again.

Is there a sensor telling this fan when to work?

When is it supposed to work?
I know it is supposed to run on cold start.
But when is it to be running other times???

I know this fan is working. but sometimes it does not come on at the correct time????


HELP.