Volvo Penta diesel engine tach

[Moonlight Lady]

I replaced the engine tachometer on the instrument panel of my Dufour 36 sailboat. It has a Volvo Penta MD2030 diesel engine so I ordered the appropriate replacement tach. I installed it and it doesn't work. I noticed that on the engine hours panel of the tach its says "CODE". I am thinking that I need to somehow program the unit with the previous engine hours to get it to work. There were no instructions provided on how to do this. Does anyone know how to do this or if there is some other issue?