Coolant Reservoir / Tank / Bottle Cap 3C0121321 for Audi, Porsche, Volkswagen

This OEM Coolant Reservoir Cap (Part Number 3C0121321) plays a crucial role in the coolant system of various Volkswagen and Audi models, securely sealing the tank to maintain optimal pressure and prevent coolant loss. It is typically located at the top of the coolant reservoir, ensuring efficient engine cooling. Compatibility includes 2020-2024 Volkswagen Atlas, Arteon, GTI, and 2016-2024 Audi A3, Q5, and A8 models, among others. Common issues that may necessitate replacement include damage from wear or a non-functioning cap that leads to overheating. Other names include Radiator Cap and Reservoir Cap. This genuine part ensures reliable engine performance and longevity. --- The 3C0121321 OEM Coolant Reservoir Cap is essential for maintaining proper pressure in the cooling system of various Audi and Volkswagen vehicles. Located atop the coolant reservoir, this cap prevents coolant leakage and aids in sustaining engine temperature. It's compatible with models like the 2020-2024 Audi Q3 and Volkswagen Tiguan as well as numerous others spanning several years. Replacement is often required if the cap is worn, cracked, or fails to seal, potentially causing overheating issues. Also referred to as a Radiator Cap or Reservoir Cap, this factory-original part helps ensure optimal engine performance and reduces the risk of damage. --- The OEM Coolant Reservoir Cap (Part Number 3C0121321) maintains essential pressure in the cooling system for various Volkswagen and Audi models. Positioned on the coolant reservoir, this cap prevents coolant evaporation and leakage. It's compatible with 2020-2024 Volkswagen Atlas, GTI, and Audi Q5 and Q8 models, among others. If the cap becomes damaged or does not close tightly, it can lead to overheating or coolant loss and should be replaced promptly. This authentic part, also known as a Radiator Cap or Reservoir Cap, ensures your vehicle operates efficiently and safeguards your engine from overheating.