Method for detecting possible under or over delivery of a micropump having at least an inlet valve, a pumping chamber with an inner pressure sensor and an outlet valve, said method comprising the determination of the pump tightness via the measurement of the pressure change in said pumping chamber during at least part of the pumping cycle when the pump is active, said method comprising furthermore the measurement of the pressure by said inner pressure sensor in said pumping chamber at least at certain intervals when the pump is inactive.
