I double checked your code, and you're spot on. For the L61 it says to replace the thermostat. Here's what my manual says:
1. Remove the intake manifold cover.
2. Drain the cooling system.
3. Remove the radiator outlet hose from the thermostat housing.
4. Remove the thermostat cover bolts and cover.
5. Remove and discard the thermostat cover O-ring seal.
1. Install a new thermostat cover O-ring seal into the recess groove.
2. Install the thermostat into housing.
3. Install the thermostat cover bolts. Tighten to 10 N.m. (89 lb in)
4. Install the radiator outlet hose to the thermostat housing.
5. Install the intake manifold cover.
6. Fill the cooling system to specifications.