Auxiliary Radiator – 4E0 121 212 B
Auxiliary Radiator for the Audi A8 (D3) platform, OE number 4E0 121 212 B. Main group 121 sub-group 212 identifies this as an auxiliary radiator. Revision index B. Cooling capacity and mounting differ between engine variants on the same platform — confirm against your engine code before ordering.
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Technical specifications
| Part Number | 4E0 121 212 B |
| SKU | AUD-4E0121212B |
| Brand | |
| Category | Radiators |
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Customer reviews
Verified feedback from Audi owners and independent workshops.
3.7
6 reviews
Greta Weiss
July 12, 2026
Holds pressure beautifully
Went on my Q5 FY 2.0 TDI at 79k miles. The core is thicker than the unit it replaced and the fin density is noticeably higher. I flushed the system properly and refilled with the correct G13 before bleeding. Result is intake temps dropped noticeably on a long motorway pull. Would order again without hesitation.
Elena Novak
June 15, 2026
Straight swap
Ordered this for my A4 B8.5 after the original gave up at 142k. I pressure tested it to 1.4 bar before fitting and it held without a drop. I flushed the system properly and refilled with the correct G13 before bleeding. Result is the gauge sits dead centre now even in traffic on a hot day.
Kwame Ibrahim
June 14, 2026
Works, but watch the seams
Ordered this for my A3 8P after the original gave up at 95k. I flushed the system properly and refilled with the correct G13 before bleeding. A weep appeared at the end tank seam after a few heat cycles. That said, the gauge sits dead centre now even in traffic on a hot day. Good part, minor niggles.
Aisha Delgado
April 19, 2026
Better core than the original
Second one of these I have bought, this time for the Q3 8U. I pressure tested it to 1.4 bar before fitting and it held without a drop. I bled it through the proper procedure and it has held level ever since. Result is the coolant level has not moved in four months.
Camille Bauer
October 11, 2025
Fins bent in transit
Bought for a 2020 A6 C8. Several fins arrived flattened because the box had almost no internal padding. Expected better given the cost.
Yara Osei
September 26, 2025
Fits, but budget a new fan shroud
Fitted to my 2009 Q5 8R. Front end off, old one out, this one in over a long Saturday. The core is thicker than the unit it replaced and the fin density is noticeably higher. On balance the gauge sits dead centre now even in traffic on a hot day. Fine for the money, with that one caveat.