yes you do because you need to know your speed limit
No.
Need a new speedometer or speedometer cable.
Yes
Replace the speedometer cable. Better yet, replace the car. I had this problem in my 94 acclaim. Somehow it had gotten severed and no new part was needed. Take it to a mechanic you trust and all it will cost you is labor. No need to replace the car.
I assume it's working and you just want to check the calibration of the speedometer. I recommend you use a GPS to check it since those devices have a speed indicator included in their many features. If your speedometer is indicating zero when the car is moving, you likely need a new speedometer. If it's reading zero when the car is moving, try clapping the dash above the instrument to see if the speedometer moves off zero. If it does, then you 100% need a new one. If it doesn't, then you 90% need a new one because you have about a 10%chance that it's the car's speed sensor which might be in the transmission. Not a big deal ($) that, the bigger deal ($$$) would be the speedometer itself.
Not knowing the year, make and model vehicle it limits how much we can help you. If the speedometer cluster is digital and both the speedometer and odometer is not working I would suspect the vehicle speed sensor is at fault. If only the speedometer is not working I would suspect the dash cluster is at fault.
The problem would be that the car is messed up
Because its a piece of crap car and u need to grow a pair and get a v8 if u think ur fast.
What year, model, make is your car? it could be anything from the computer to the wire coming from your wheel.
=A Gage is gun a 12 gage=
it means the circuit of car is short........
Nope, bet it was the other way around... Your speedometer stopped working and your check engine light came on. A broken speedometer (don't know what car so I can't pinpoint it) will cause a whole bunch of codes.