Parts for your 2006 Toyota Prius-Heater hose

2006 Toyota Prius heater hose — what it does and how to look after it

Heater hoses are definitely used on the 2006 Toyota Prius (NHW20). Toyota’s NHW20 Repair Manual (Cooling/Heater sections), the Toyota Electronic Parts Catalogue (which lists “Hose, Heater No.1/No.2” for NHW20), and Toyota’s New Car Features manual describe the engine coolant‑to‑heater‑core circuit. Toyota’s service bulletin addressing the coolant flow control valve (DTC P1121) also details this heater loop. So, a heater hose is relevant and fitted to this model.

On a 2006 Prius, the heater hose’s job is simple but vital: carry hot engine coolant to and from the cabin heater core so the car can deliver warm air on chilly mornings. Unlike the separate inverter cooling loop, the heater circuit is part of the engine cooling system and works with the Prius’s three‑way coolant control valve. When the driver selects heat, coolant is routed through the heater core via those hoses, translating engine warmth into toasty airflow inside the cabin.

Because hoses age with heat, pressure and time, they deserve a look during routine servicing. Under the bonnet, check the two heater hoses running to the firewall for: surface cracking, swelling or soft spots