[Sinner]

On top of script write:

PHP код:

#define PRESSED(%0) (((newkeys & (%0)) == (%0)) && ((oldkeys & (%0)) != (%0))) 


Then:

PHP код:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if(PRESSED(KEY_SUBMISSION))
    {
        new id = GetPlayerVehicleID(playerid);
        if(id)
        {
            SetVehicleHealth(id, 1000);
            SendClientMessage(playerid, 0x00FF00, "Vehicle Repaired!");
        }
    }
    return 1;
} 


This will fix the car whenever the player pressed the "KEY_SUBMISSION" (which is '2' or '+' by default)