I don't know how the flow "sensor" works, but IF it is just a pressure sensitive micro switch, simply attaching a wire across the terminals would fool the controller.

If anyone reading this can disconnect their flow sensor and ohm it out with/without pump running, that would answer the question.

Is your controller run off the timer controlled pump power (like their manual says it should be)?
That would make the flow switch somewhat academic, except for total pump failure (that doesn't blow the circuit breaker)

Mike K