reset my ecu?

[dydigital]

How do i reset me ecu after a the managment light has come one?

[Tomcat]

You can try disconnecting the battery over night, what year is the 850?.

[nobananas]

Early 850's can be reset using the under bonnet diagnostics socket, later ones (with the obd socket under the coin store by gear lever) either unplug the ecu or as TC says disconnect the battery. Obviously if the MIL comes back on you still have a fault !