[cas951]

Everyone covered most of the items you need to check. If the Engine temp is constantly high and you've already checked that the airflow to the radiator is not clogged these are your other possibilities.

1. Thermostat can operate normally but they can be sticky and open partially. This will cause your engine temps to be higher than normal since the flow of coolant is limited.

2. I have not replaced a water pump on a Boxster but if the water pump material is similar to BMW's and Vw's this could be at fault. BMW and VW waterpump uses a hard rubber compound impellers. These wear out overtime and can no longer push the required volume of coolant to cool the engine and cause your temp to be higher than normal. VW had a recall on their waterpump due to this and BMW's require to change at 50k.

Inspecting either of these route will require you to get into the engine compartment and also drain the coolant. Probably a good time to replace both.

I have seen both BMW and VW pumps when they failed. The impeller was completely rounded