2002 Audi A6 Thermostat

The thermostat is located in the engine block just to the side of the water pump underneath the housing where the upper radiator hose is attached.

Remove the lower engine shield.
Place a large drain pan under the vehicle to collect the coolant.
Remove the radiator cap and drain the cooling system into a suitable container.
Place a large drain pan under the engine block drain located at the bottom of the engine near the vicinity of the flywheel and the oil pan.
Drain the engine block coolant into a suitable container.
Place the (hood) lock carrier in the 'service position'. For additional information, please refer to the following topic(s): Body And Trim, Service Position, Front Bumper, Hood Lock Carrier.
Remove the accessory drive belt. For additional information, please refer to the following topic(s): General Information And Maintenance, Routing Maintenance And Tune-Up.
If installed, remove the upper front engine cover.
Remove the toothed camshaft drive belt from the right side cylinder head to allow enough access to remove the thermostat housing. Cover and protect the drive belt from residual coolant.
Remove the mounting fasteners; remove the housing, then the thermostat.