URO 8K0-121-405 R Engine Coolant Expansion Tank Reservoir

The URO 8K0-121-405 R is a direct-fit replacement coolant expansion tank, also known as a coolant reservoir or overflow tank, engineered for Audi vehicles. This component plays a critical role in the engine cooling system by accommodating coolant volume changes as the fluid heats up and contracts during normal engine operation.

Over time, the factory expansion tank is subjected to repeated thermal stress cycles that can cause the plastic to become brittle, crack, or develop leaks. A failed or leaking expansion tank can result in coolant loss, low coolant warnings, and ultimately engine overheating if left unaddressed. Replacing a damaged tank promptly helps protect the engine from costly heat-related damage.

Key Features:

• Direct OEM replacement for part number 8K0-121-405 R
• Designed to maintain proper coolant levels and system pressure
• Manufactured by URO, a trusted supplier of European replacement parts
• Cost-effective alternative to genuine OEM pricing
• Cross-reference part numbers: 8K0121405R, 8K0-121-405-M, 8K0121405M, 8K0121405P

Important Note: When refilling the cooling system, always use the coolant type specified for your Audi. European vehicles typically require a specific G12 or G13 compatible antifreeze formula to prevent premature corrosion and seal degradation.