This is a controll unit for a heating system when the engine is not running. Gasoline is burned in a little burner which heats up the coolant. A little electric pump moves the water around and you have a perfectly heated car.

There is also a time clock so you can set it at 6.30 and get a heated car with a heated engine at around 6.50.

This looks like factory installed, the manufacturer ist Webasto.

There is also a manufacturer Eberspächer (right here from Esslingen where I live)

Their Standheizung is of less quality and never was factory installed. Only aftermarket.

BTW: Code 972 very often had that heating device. Made surveillance a little less frisky.

Kind regards
Eberhard