WHAT IS O/D OFF?

O/D means overdrive. It changes the gear rations to give you a little extra ooomph when you need it. The engine will stay in gear longer to give you a little more power. There should be a button on your dash or sometimes on the gear shifter itself that will control overdrive. Generally you will want to leave it on, it will help fuel economy and will be better for the engine.

Thank you very much, it was helpful.

hi my 2002 mazda 626 will not go in drive with the overdrive button on but turned off it will go in drive could it be the sensor

Thank you