Does the speed sensor input for the OBC and the speedometer/odometer?

My OBC always reads the correct speed, but speedometer/odometer will act a bit wild after the car has been driven for ~20min, then settle in at double speed on the speedometer. The odometer also reflects the higher speedometer reading. I was assuming that the speed sensor fed both systems, so if one is working properly, logic tells me that it's not the sensor.

I posted last week about capacitors and I was considering changing them out, but in the spirit of starting simple, I would rather change out a part that doesn't involve a circuit board.

I'm getting close to admitting defeat and paying someone to diagnose it