Coolant Bottles / Expansion Tanks

Coolant expansion tank bottle.
This genuine coolant expansion tank is the original-spec reservoir that forms part of the Taycan’s coolant system, responsible for managing coolant volume and pressure as the system heats and cools. Manufactured by Porsche to strict OEM standards.

Fits:
Porsche 9J1.1 Taycan 2020 - 2024

Diagram ref no 1

The coolant expansion/overflow reservoir for the Taycan’s coolant system. It collects and stores excess coolant from the closed-loop cooling circuit when temperature changes cause expansion. It also provides a visible coolant level reference and a refill point when topping-up is required.

This coolant tank:
• Accepts excess coolant as it expands under heat, preventing over-pressure in the cooling system.
•  Allows coolant to return to the system when temperatures drop, helping maintain proper coolant volume and pressure.
•  Provides a clean, secure housing that resists heat, pressure, and coolant chemistry - preventing leaks and degradation.
•  Maintains correct coolant level and system integrity, vital for thermal management of batteries, motors, and inverter cooling.

When to replace.  You should consider replacing the coolant expansion tank if:
•  The original shows cracks, discoloration, deformation, or leaks.
•  Coolant level drops unexpectedly without visible external leak - indicating internal crack or cap failure.
•  The tank becomes brittle, warped, or chemically aged due to coolant exposure and heat cycles.
•  You are restoring or servicing the cooling system, or performing maintenance/replacement of hoses, pumps or thermal components.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

9J1121407A

The product you are viewing cross references to these numbers

Coolant expansion tank bottle.
OE Match coolant expansion (overflow) tank that forms part of the Taycan’s closed cooling system. It serves as a buffer reservoir for coolant volume changes caused by temperature fluctuations in the system. It also provides a visible coolant level reference and a fill point for maintenance. As a direct-fit replacement, it integrates with the factory hoses, clamps, and sensors without modification.

Fits:
Porsche 9J1.1 Taycan 2020 - 2024

Diagram ref no 1

The coolant expansion/overflow reservoir for the Taycan’s coolant system. It collects and stores excess coolant from the closed-loop cooling circuit when temperature changes cause expansion. It also provides a visible coolant level reference and a refill point when topping-up is required.

This coolant tank:
•  Accepts expanding coolant when temperature rises, preventing over-pressure in the cooling circuit.
•  Stores slightly extra coolant, which returns to the main system when temperatures drop - maintaining consistent coolant levels.
•  Provides a safe, sealed reservoir that resists coolant chemistry, temperature, and vibration - preventing leaks or contamination.
•  Offers a sight-glass or translucent body (or level markings), making coolant level checks simple and straightforward for maintenance.

Over time, coolant expansion tanks may develop cracks, stress fractures or leaks due to pressure cycling, temperature variation, or material fatigue - particularly in high-performance or electric cooling systems. If the expansion tank fails, you risk coolant leaks, pressure loss, overheating or inadequate coolant circulation.

An OE Match replacement restores proper system pressure management, coolant containment, and leak-free operation. It protects the drivetrain’s thermal management integrity, supports battery/motor cooling stability, and helps prevent costly damage or component failure.

When to Replace Consider replacing the expansion tank if:
•  The original shows visible cracks, deformation, or plastic fatigue.
•  There is coolant loss or leakage under the car or around the reservoir.
•  The system shows erratic coolant-level changes or pressure anomalies.
•  You are performing cooling-system maintenance, overhaul, or upgrades.
•  You notice discoloration, brittleness, or internal contamination in the tank material.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

9J1121407A

The product you are viewing cross references to these numbers