I believe you have the AC MicroCommand system. If so, check the cables and small wires to pump motor # 2 and its inverter.
The code means that either the sensor is reporting more than 4000 RPM OR that the motor isn't spinning when current is sent to it OR that the motor is spinning in reverse.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.