The Manifold Absolute Pressure (MAP) Sensor is the “key” sensor on Hondas. It controls timing (similar to the old vacuum advance on distributors) and air/fuel mixture, depending upon manifold pressure changes. Like any transducer, it converts energy from one form to another. Here, it converts throttle body vacuum pressure changes into fluctuating electrical current signals to the ECM. They tend to be very expensive and very reliable--I've never seen one go bad.