Tech description
There are seven (7) codes listed on the service manual for the P1647 code. Try reseting the code first, and if the code comes back, check fuses and the Engine Control Module (ECM) connector.
P1647 HONDA OBD Code Description
P1647 – Power Command Signal Circuit Low Input
P1647 – Power Command Signal Circuit High Input
P1647 – Engine Torque Signal Circuit Low Input
P1647 – Engine Torque Signal Circuit High Input
P1647 – Mode Signal Circuit 1 Low Input
P1647 – Mode Signal Circuit 1 High Input
P1647 – Mode Signal Circuit 2 Problem