Genuine Subaru 99078AA090 Engine Coolant Bypass Hose Heater Pipe

The Genuine Subaru 99078AA090 is an OEM engine coolant bypass hose, also known as a heater pipe to right cylinder head. This direct-fit replacement hose is manufactured to original factory specifications, ensuring a precise fit and reliable performance in the engine cooling system.

The coolant bypass hose plays a critical role in engine temperature regulation. It routes coolant between the water pump and thermostat housing, allowing coolant to circulate around the engine block and cylinder head when the thermostat is closed during cold starts and warm-up cycles. This prevents overheating and helps the engine reach optimal operating temperature efficiently.

Key Features:

• Genuine Subaru OEM part — exact factory replacement
• Functions as heater pipe to right cylinder head
• Maintains proper coolant flow and engine temperature regulation
• Manufactured to OEM material and dimensional specifications
• Direct-fit replacement — no modification required
• Backed by Subaru manufacturer warranty

Replacing a cracked, brittle, or leaking coolant bypass hose with a genuine OEM part helps prevent coolant loss, engine overheating, and costly engine damage. Part number: 99078AA090.