[Boolean]

It keeps sending the message because the health stays below 500. If you want it to send one message you'll have to use another variable. For example:

pawn Код:

public OnPlayerUpdate(playerid)
{
    if(IsPlayerInAnyVehicle(playerid))
    {
        new Float:health;
        new vehid = GetPlayerVehicleID(playerid);
        new message = GetPVarInt(playerid, "Message");
        GetVehicleHealth(vehid, health);
        if(health <= 500 && message == 0) // Checks if we didn't receive a message yet
        {
            SendClientMessage(playerid, -1, "BROKEN");
            SetPVarInt(playerid, "Message", 1); // Message sent
        }
    }
    return 1;
}