Audi A4 B9 A5 5F A6 C8 Auxiliary Coolant Radiator 2.0 TDI 8W0145804A

Audi A4 B9 A5 5F A6 C8 Auxiliary Coolant Radiator is an original cooling system component from the Water Radiators group, designed specifically for 2.0 TDI diesel engines. As a used OEM part, it ensures factory-fit, stable operating parameters, and predictable performance in real-world road conditions.

Specifications and technical data

• SKU: 8W0145804A-1
• Mark: Audi
• Condition: Used
• OEM Part Number: 8W0145804A
• Substitutable numbers: 8W0145804A, 8W0 145 804 A
• Part type: Radiator
• Category: Radiators

Purpose and role in the cooling system

The auxiliary coolant radiator in Audi A4 B9, A5 5F, and A6 C8 models is responsible for increasing heat dissipation efficiency from the 2.0 TDI engine, especially under highway loads and dynamic driving conditions. It supports the main radiator, stabilizing the coolant temperature and reducing the risk of engine overheating.

Using a dedicated, factory-made radiator translates into:

• maintaining optimal engine operating temperature across a wide range of loads,
• more uniform heat distribution within the cooling system,
• better protection of cooperating components (seals, hoses, housings),
• stability of parameters in high ambient temperature conditions.

Benefits of using an original Audi water radiator

The original auxiliary coolant radiator for the 2.0 TDI engine was designed for specific Audi models, which means precise fitment with factory mounts and predictable coolant flow throughout the system. Eliminating the need for installation modifications minimizes the risk of leaks and assembly issues.

Key advantages include:

• maintaining the factory cooling characteristics specified by the manufacturer,
• compatibility with the existing cooling system architecture in the Audi A4 B9, A5 5F, and A6 C8,
• consistency with other OEM components, which facilitates diagnostics and service.

Condition, selection, and installation

The presented radiator comes from the used OEM parts segment, which allows for combining controlled repair costs with maintaining the original cooling system design. When selecting the component, it is worth paying attention to compatibility with the 2.0 TDI engine version and the specific vehicle configuration.

In practice, the installation of the auxiliary coolant radiator in these Audi models involves:

• connecting to the existing coolant circuit,
• using factory mounting points in the front of the vehicle body,
• checking system tightness and bleeding the system after installation.

Operation in high temperatures

In vehicles with the 2.0 TDI engine, the auxiliary coolant radiator is of particular importance during the summer, when the thermal load on the system increases. Stable operation of this component helps maintain a safe temperature margin for the engine, which promotes longer service life of the engine and its accessories.

If you want to better understand how summer conditions affect the cooling system and when it is worth choosing used components, check out our guide Summer heat vs. cooling system: used radiators and fans as a guarantee of savings.

Cooling system expansion and related components

If you are planning a comprehensive repair or upgrade of the engine area in your Audi and need other elements from the same group, such as additional cooling modules, coolant hoses, or auxiliary heat exchangers, check out the available parts in the Audi Water Radiators category.

When making a decision about choosing a used OEM component, it is also worth reading the practical tips regarding the advantages of original components over aftermarket replacements, described in the article 5 reasons why a used OEM part is a better choice than an aftermarket replacement.