Audi A8 D4 Fuel Injector Rail Left N/S Injection Unit 4.2 TDI Diesel 057130089Q

Audi A8 D4 Fuel Injector Rail Left N/S Injection Unit 4.2 TDI Diesel is a precision fuel system component designed for diesel engines in the luxury Audi sedan. As part of the Lines, hoses and pipes group, it is responsible for the stable distribution of fuel to the injectors on the left side of the engine unit, which directly affects the refinement and performance of the 4.2 TDI engine. This used OEM component allows for maintaining the factory operating characteristics of the injection system at a reasonable repair cost.

Specifications and technical data

• SKU: 057130089Q
• Mark: Audi
• Condition: Used
• OEM Part Number: 057130089Q
• Substitutable numbers: 057130089Q, 057 130 089 Q
• Location on the vehicle: Left
• Fuel type: Diesel
• Category: Hoses, Lines & Pipes

Purpose and function in the fuel system

The fuel injector rail on the left side of the 4.2 TDI engine plays a key role in distributing high-pressure fuel to individual injectors. A properly selected rail ensures:

• stable pressure throughout the supply circuit on the left side of the unit,
• even fuel dosing to the cylinders,
• proper cooperation with diesel engine accessories,
• maintenance of combustion parameters in accordance with the manufacturer's specifications.

Thanks to the preservation of the original geometry and connections, the rail is matched to the engine bay architecture of the Audi A8 D4 with the 4.2 TDI unit, which facilitates installation and reduces the risk of leaks.

Compatibility with the 4.2 TDI Diesel engine

The presented rail has been designed to operate in a diesel engine fuel system where precise fuel pressure maintenance is required. The design adapted to the 4.2 TDI unit allows for maintaining:

• proper injector operating characteristics,
• correct response to load and changes in fuel demand,
• compliance with factory diesel engine management.

The positioning on the left side of the vehicle is important when selecting parts – using the correct rail relative to the installation side minimizes problems with routing lines and integration with other system components.

Installation and operational characteristics

The fuel injector rail on the left side in the Audi A8 D4 has been developed as a common rail system component, working with high-pressure lines and injectors. In practice, this means:

• maintaining factory mounting points in the engine bay,
• compatible connections for lines and injectors,
• possibility of installation in place of the original rail without structural modifications.

The used OEM element allows for restoring the proper operation of the fuel system in the event of damage or leakage of the existing rail, without the need to interfere with other components.

Benefits of using an original fuel injector rail

Using an original fuel injector rail in the Audi A8 D4 4.2 TDI brings a number of practical benefits:

• Factory fit – maintaining compatibility with the engine and fuel system design,
• consistent cooperation with diesel accessories, including injectors and the high-pressure pump,
• reducing the risk of starting problems, power loss, or uneven engine operation,
• possibility of economical repair while maintaining parameters close to factory specifications.

For users who want to maintain a high standard of engine performance in the Audi A8 D4, choosing an original fuel injector rail is a technically sound and predictable solution in operation.

Fuel system expansion and additional information

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 fuel lines, flexible supply hoses, or rigid high-pressure pipes, check the available parts in the Audi Lines, hoses and pipes category.

If you are also interested in improving driving comfort and the overall value of the vehicle through interior modernization, it is worth checking out the guide on selecting branded seats from dismantling – you will find practical tips in the article Interior metamorphosis: how branded seats from dismantling affect comfort and car value.