BMW G20 G21 Fuel Tank Breather Line Pipe Hose Fuel Unit Petrol 8663978

BMW G20 G21 Fuel Tank Breather Line Pipe Hose Fuel Unit Petrol is an original fuel system component designed for 3 Series G20/G21 models with petrol engines. Engineered by BMW, it ensures proper venting of the fuel line, which translates into stable engine performance and correct fuel vapor emission control.

Specifications and technical data

• SKU: 8663978
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 8663978
• Substitutable numbers: 8663978, 13908663978
• Fuel type: Petrol
• Category: Hoses, Lines & Pipes

Purpose and function in the fuel system

The fuel tank breather line in the BMW G20/G21 is responsible for the controlled flow of fuel vapors between fuel system components. Proper operation of this component reduces the risk of overpressure in the lines, facilitates engine starting, and stabilizes operating parameters under varying loads.

Thanks to its precisely selected diameter and shape, the line maintains tightness and the correct direction of vapor flow, which is essential for proper interaction with the engine management system and emission control system.

Construction and fitment for BMW G20/G21

The element belongs to the Lines, hoses, and pipes group, meaning it has been designed to operate in a fuel environment, taking into account resistance to petrol and temperature changes in the engine bay. Factory fitment for the BMW G20 and G21 allows for installation in original mounting points without the need for modifications.

Properly profiled sections of the line minimize stress during engine operation and body vibrations, which reduces the risk of micro-cracks and leaks in the long term.

Application in petrol vehicles

The line is intended for use with petrol-type fuel systems, where precise venting and fuel vapor control are required. Proper selection of the component for the fuel type is crucial for safety, pressure stability in the lines, and the correct operation of sensors and valves in the fuel system.

Using a dedicated line instead of universal parts reduces the risk of installation errors, leaks, and electronic vehicle diagnostic issues.

Condition of the item and benefits of choosing OEM parts

The offered line comes from the BMW parts group and is a used component, which in practice allows for an economical repair while maintaining original geometry and compatibility with the factory fuel system. Choosing an OEM component ensures compliance with factory operating parameters and predictable behavior during long-term use.

For workshops and individual users, this means easier identification in catalogs, simpler installation, and a lower risk of fitment issues compared to aftermarket replacements of uncertain origin.

System expansion – other BMW lines, hoses, and pipes

If you are planning a comprehensive repair or upgrade of the fuel system area in your BMW and need other elements from the same group, such as additional fuel lines, breather hoses, or return pipes, check the available parts in the BMW lines, hoses, and pipes category.

How to verify compatibility using OEM numbers

When selecting a breather line for a specific BMW G20/G21 version, it is worth verifying compatibility using the OEM number and interchangeable numbers, using the manufacturer's catalogs or specialized search engines. This avoids installation problems and ensures full compatibility with the fuel system of a given vehicle.

If you want to streamline the parts selection process and reduce the risk of mistakes when shopping online, a practical guide on verifying components by factory numbers will be helpful – check the material: Risk-free online parts shopping – 5 proven ways to verify component compatibility using OEM numbers and paint codes.