Radiator – 8K0 121 251 AJ
Radiator for the Audi A4 (B8) platform, OE number 8K0 121 251 AJ. Main group 121 sub-group 251 identifies this as a radiator. Revision index AJ. 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 | 8K0 121 251 AJ |
| SKU | AUD-8K0121251AJ |
| Brand | |
| Category | Radiators |
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3–5 business days. Free on orders over $150.
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Order before 2 PM for next business day delivery.
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Return unused parts within 30 days for a full refund.
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Customer reviews
Verified feedback from Audi owners and independent workshops.
3.7
3 reviews
Greta Lindqvist
February 13, 2026
Straight swap
Second one of these I have bought, this time for the A5 F5. 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. Result is the coolant level has not moved in four months. Cannot fault it.
Zara Okonkwo
February 3, 2026
Perfect fit, no modification
Went on my S3 8V 1.4 TFSI at 133k miles. The plastic feels substantial rather than the brittle stuff that cracks at the neck. I bled it through the proper procedure and it has held level ever since. Result is the gauge sits dead centre now even in traffic on a hot day. Will be back for the other side.
Stefan Okonkwo
October 8, 2025
Seeped from the end tank
Fitted to my 2011 Q3 8U. A weep appeared at the end tank seam after a few heat cycles. All the mounting points and hose stubs lined up without any persuasion. Expected better given the cost.