X AUTOHAUX Coolant Reservoir Tank 5Q0121407A with Cap & Sensor for Audi/VW (2012-2020)

Overview

Introducing the X AUTOHAUX coolant reservoir tank, a robust aftermarket replacement engineered to align with OEM geometry and connector layouts for a range of Audi and Volkswagen models. This kit includes the cap and a 2-pin sensor, with the part number 5Q0121407A and compatible variations 5Q0121407D and 5Q0121407G where applicable. Built to withstand daily driving demands, it offers a reliable pathway to maintain proper coolant management within the cooling loop.

Why this reservoir matters

In everyday driving, the reservoir handles coolant expansion and return to the radiator, helping the cooling system respond to temperature swings during city commutes and longer highway drives. While no aftermarket part can guarantee a specific outcome, a properly matched reservoir may contribute to steadier engine temperatures and reduced stress on cooling components when the system is operating as intended.

Compatibility and function

• Fits Audi A3 8VA/8VF (2012–2020), plus related models such as Q2 (2016–2020), Q3 (2018–2020), TT MK3 (2014–2020), Arteon (2017–2020), Golf MK7 (2012–2020), Seat Ateca (2016–2020), and Passat 3G (2014–2020).
• Includes cap and a 2-pin sensor for straightforward installation and monitoring integration.

What’s included and key features

• Reservoir tank, protective cap, and a 2-pin sensor.
• Durable construction designed to resist rust, oxidation, fluid loss, and deformation over time.
• OEM-match geometry to support safe mounting and hose connections.

Durability and design details

Crafted with rugged materials, this reservoir is built to endure the vibration and heat of daily driving. The included cap seals securely to minimize coolant loss, while the sensor provides a reliable signal for level checks under different engine temperatures.

Installation guidance

1. Ensure the engine is cool before starting; remove the bolts holding the old tank.
2. Let residual coolant drain into a pan, remove the old piece, and prepare the hose connections.
3. Position the new reservoir, reconnect hoses, tighten clamps, and reinstall any mounting hardware.
4. Recheck all connections and perform a careful coolant refill, then run the engine to verify proper function.