Non-toxic coolant is available at local auto parts stores. Although the coolant is non-toxic when fresh, proper disposal of used coolant is still required. First, drain the coolant. Next, disconnect the electrical connector from the sending unit. On four-cylinder models the Engine Coolant Temperature (ECT) sensor also functions as the coolant temperature sending unit - it's located on the left (driver's) end of the cylinder head. The coolant temperature sending unit no. 2 on V6 engines is located in the water outlet at the passenger's side of the engine - use a deep socket to remove it (sensor no. 1 is threaded into the lower tank of the radiator). Using a deep socket or wrench, remove the sending unit. Install the new unit and tighten it securely. Do not use thread sealer as it may electrically insulate the sending unit. Reconnect the electrical connector, refill the cooling system, and check for coolant leakage and proper gauge function.