I have a Honda Civic 2000 EX with a malfunctioning speedometer that gets stuck at 20MPH. I wanted to know if any of you had any similar symptoms to mine, I have read that the speed sensor on these models tend to fail but I feel it could be more than that. Sometimes it shows the correct speed while driving but not often.

The symptoms is as follows:
When the car is completely off the needle rests on 0MPH
When the car is on but the engine is off the needle jumps up to 20MPH
Unplugging the speed sensor cable while car on but engine off sets the needle to 15MPH.

We looked at the circuit board and it seems like it was replaced but I think the replacement is malfunctioning as well. All other instruments are working perfectly except for total mileage counter.

 

Sounds like the sensor is bad.