What do code 31-02 mean for my 2001 handa odossey

The OBD code P3102 means there is a "transmission control ECU malfunction".

You may be experiencing a hard shudder when you turn off the engine.

Possible causes could include: Faulty fuse or fuses, faulty wiring and/or Connector(s) from/to Intake Manifold Flap Motor or a faulty Intake Manifold Flap Motor.

Your possible solutions could include: Check for blown fuses, check wiring and/or connector(s) to and from the Intake Manifold Flap Motor, check or replace the Intake Manifold Flap Motor. You can also perform an Output Test.