Heating and Cooling› Overflow Tanks and Catch Cans

Genuine

Coolant Expansion Tank

$160.00

SKU: 4E0121403G

Special Order
Special Order
Ships in 4–6 weeks
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Easy — 1–2 hours

Overview

The Genuine 4E0121403G is a plastic coolant expansion tank designed for various Audi A8 and S8 models. This component serves as an overflow reservoir for the engine's cooling system. It includes a level sensor for monitoring coolant status.
Show original supplier description
The Genuine 4E0121403G coolant expansion tank is constructed from durable plastic and is specifically designed for Audi A8 and S8 D3 models equipped with the 4.2L V8 engine. This genuine OEM part functions as the engine's coolant overflow and expansion reservoir, crucial for maintaining optimal operating temperatures. It comes complete with an integrated level sensor to alert the driver to low coolant conditions. Fitment information indicates compatibility with a range of model years, including: * Audi A8 4.2L V8 A/T Quattro Base Sedan: 2005, 2006, 2007, 2008, 2009, 2010 * Audi A8 4.2L V8 A/T Quattro L Sedan: 2004, 2005, 2006, 2007 * Audi A8 Quattro Base Sedan 4.2L V8: 2003, 2005, 2006 * Audi A8 D3 S8 Quattro: 2004-2010 * Audi A8/S8 D3 Quattro: 2006-2010 * Models from 2002 to 2010, with specific reference to models from chassis # 4E-3-000001 for 2003 models. It is important to verify fitment using the vehicle's VIN number, as some sources recommend this step to ensure compatibility. Always confirm the part number against your existing component before installation.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

Fitment Guaranteed

Don’t gamble
on fit.

Log your build in the MOTORMIA app and we’ll guarantee this part fits your exact setup — or your money back, return shipping covered.

Available on iOS & Android

Specifications

BrandGenuine
Part Number4E0121403G
CategoryHeating and Cooling
5,000+ Trusted brands
1M+ Enthusiasts
5M+ Parts sold
(760) 282-4645 hello@motormia.co

Buy with Confidence

Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

View Full Return Policy

Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

View Full Shipping Policy