URO 03L-121-111Q Engine Coolant Thermostat Assembly with Housing

The URO 03L-121-111Q is an engine coolant thermostat assembly designed as a direct OEM-replacement unit. This complete assembly includes the thermostat, housing, and gasket, making it a straightforward replacement for worn or failed cooling system components.

How It Works:

The thermostat is a critical component in the engine cooling system. When the engine is cold, the thermostat valve remains closed, allowing coolant to circulate within the engine block until it reaches optimal operating temperature. Once the engine reaches its target temperature, the valve opens to route coolant through the radiator, where it is cooled before returning to the engine. This continuous regulation prevents both overheating and insufficient warm-up.

Key Features:

• Complete assembly — includes thermostat, housing, and gasket
• Operating temperature range: 87°C–135°C (189°F–275°F)
• OEM-specification wax-pellet actuated valve mechanism for precise temperature response
• Direct bolt-on replacement — no modification required
• Manufactured to OEM dimensions and tolerances

OEM / Cross-Reference Part Numbers:

• 03L-121-111 Q
• 03L121111Q
• 03L 121 111 Q

Note: O-ring is sold separately. After installation, bleed any trapped air from the cooling system to ensure proper pressurization and coolant flow.