Audi A4 Radiator: Specs, Fitment & Common Faults
On the A4, a confirmed safety recall genuinely addressed water pump issues, with problems documented occurring between 30,000 and 70,000 miles — plus an important clarification that genuine water pump-caused overheating is actually rare.
Illustration for editorial purposes
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OEM Part Number: 8K0121251AB (as quoted in catalogue listings — confirm via VIN) — aftermarket radiators Nissens 60322 / Valeo 701228
| Radiators (aftermarket) | Nissens 60322 (720 x 470 x 32 mm, aluminium core with soldered fins, plastic tanks, built-in oil cooler; fits the 4.2 V8 RS4 Avant B8 and the S5/RS5 8T3/8F7 only); cross-refs Valeo 701228, NRF 53065, Mahle CR 1133 000S, Prasco AD620R011, Kale 345860. Ava Quality Cooling AI2299 (235 x 188 x 26 mm, soldered fins, plastic tank) is the small auxiliary radiator fitted to the 2.7 TDI, 3.0 TDI quattro and S4 on the B8, not the main radiator; cross-refs AKS Dasis 480072N, Diederichs DCM1493, Autogamma 105433, AHE 102.181. |
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| Core sizes & variants | The main radiator for the mainstream 1.8 TFSI, 2.0 TFSI and 2.0 TDI B8 cars (and the manual/Multitronic split within them) is a different, shallower core from the 32 mm RS4 unit above; the V6 diesels add the AI2299-sized auxiliary cooler beside the main radiator. |
| Genuine (OE) numbers quoted | 8K0121251AB; 8K0121251AM; 8K0121251S (RS4/S5 main radiator); 8K0121212; 8K0121212A; 8K0121212B (V6 TDI auxiliary radiator) |
| Fitment notes | For a four-cylinder B8 or any B9, order the genuine radiator against the VIN; the RS4 unit has 38.5 mm inlet and outlet stubs and an integral oil cooler, so it will not swap onto the ordinary cars. |
Audi A4 Radiator: The Part That Keeps Everything Else From Cooking
Unglamorous as it is, the Audi A4's cooling system sits behind nearly every serious engine failure that isn't just ordinary wear — and one that went unaddressed for too long. Noticing early warning signs here is a small cost against a potentially very large one.
Audi A4 Radiator: What It Does
On the Audi A4, engine coolant sheds its heat into the passing air via the radiator, which is what keeps engine temperature in a safe working range. On automatics, it frequently pulls double duty cooling the transmission fluid through its own internal circuit — a detail that makes getting the exact part number right especially important.
Audi A4 Radiator: Watch: Replacing It
B8 front-end-off job; for B9 see https://www.youtube.com/watch?v=L5VpBZEmZog (Replacing a Leaking Radiator on a B9 Audi: 2017 A4)
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Confirmed: A Genuine Safety Recall Worth Checking Your Car Against — Audi A4 Radiator
This is genuinely worth checking directly on related model years: a confirmed recall addressed water pump issues that could cause coolant to leak from the pump housing, with problems on this platform documented occurring anywhere from as early as 30,000 miles up to around 70,000 miles.
It's also genuinely worth knowing an important clarification: genuine overheating caused directly by a failed water pump is actually quite rare. More often, overheating stems from warped cylinder heads or a weakened head gasket, frequently the lingering result of a previous overheating event.
Audi A4 Radiator: Faults, DIY Difficulty & Aftermarket Advice
These are the same regardless of make or model — see our full Radiator Guide for the three common failure modes, confirming fitment against your VIN, and OEM vs aftermarket guidance.
More Audi Radiator
The same part, covered across other Audi models.