If its an 1120 it won't be 2014, if you installed a new potentiometer it will need calibrating.
You need to get a laptop plugged into it to diagnose the issue

Hello it is series 1120 , i checked all the altitude sensors and on the screen it does not show turtle running , i checked and replaced the speed sensor on the motor but now it only runs 2km/h

Check the micro switch on the brake pedal the ends do fail on them between the operating arm and switch, I've changed quite a few on the 115 reach trucks. This will give the fault you've described and not show an error on the dash

Hello, how much slow speed you have? is it 1120 series?
If you have high mast, there is 8-meter switch which slow down the speed if mast is lifted more than that height. it doesn't show on display. there could be wire or sensor faulty. prior models had limit switch, and new ones are with proximity sensors.

if it moves very very slow less than 1 kph then it is RPM sensor on drive motor, wires also get too hot also.

Hello did you checked brake pedal?speed sensor on traction motor?