My 2005 FEH has about 17,000 miles on it, and I've noticed the ICE coolant tank level has gradually been dropping over the past year. It is about an inch and a half below the cold minimum mark. The inverter coolant tank is still right at the cold minimum mark.

Has anyone else seen a slight drop in coolant level? I most likely will make an appointment to have it checked out soon.

 

Hose connections can start seeping and water pumps (mechanical) can start to go bad(leak), esp if someone added tap water to the coolant. There is a TSB for a coolant hose rubbing but this is for the very early 05s and does not say if it applies to the hybrid.