I believe the proper proceedure for reseting it is turn key to on position, make sure trip meter is in odometer mode, press and hold the plunger in, turn key off, while still holding plunger in turn key back on, when the numbers stop unwinding to 0 turn key back off and release plunger. The next time key is turned back on the odometer will resume normal function. I believe this is correct as ive only reset mine once and will re-read the procedure before I do it again. To my knowledge it can't be permantly turned off.