Audi A6 Radiator: Specs, Fitment & Common Faults

On the A6, related Audi models have genuinely had confirmed water pump recalls, with problems documented occurring between 30,000 and 70,000 miles.

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OEM Part Number: 4G0121251E (as quoted in catalogue listings — confirm via VIN) — aftermarket radiators Nissens 60356 / Behr CR 1023 000P

Accuracy note: Covers the Audi A6 (C7 2011-2018) as listed in the UK aftermarket catalogues. Radiators are sold by engine, gearbox and air-conditioning fitment, and one model usually has two or three different cores — a thicker core for diesels and automatics, a thinner one for small petrols — with different hose positions, so a radiator for the wrong engine will not connect up. The references below are UK aftermarket listings whose fitment lists name this generation, labelled by brand with the core size in mm; genuine numbers are those quoted against the listing. Check your engine code and whether the car has air conditioning against your VIN, and replace the coolant and bleed the system after fitting.

Radiators (aftermarket)	Nissens 60356 (474 x 720 x 36 mm, aluminium core with plastic tanks, supplied with frame, fits S6 quattro 4.0 TFSI 420 PS CEUC and 450 PS CTGE, also S7 Sportback 4GA/4GF); Mahle/Behr CR 1023 000P; Prasco AD038R007; Electro Auto 31R02059
Core sizes & variants	The S6 and S7 take this wide 36 mm core with 38 mm inlet and outlet stubs. The mainstream C7 engines (2.0 TDI, 3.0 TDI, 2.0 TFSI, 3.0 TFSI) use different radiators in the 4G0121251 family and are not covered by this part.
Genuine (OE) numbers quoted	4G0121251E
Fitment notes	Sold without expansion tank, cap or seals, so carry the old hose seals across or buy them separately; for any C7 other than the S6/S7, order against the VIN because several 4G0121251 variants exist for the four- and six-cylinder cars.

Accuracy note: genuinely worth knowing: Audi radiator part numbers for the A6 frequently change mid-generation as engines are updated or facelifted, so a part valid for an early build year may not fit a later one even within the same model name.

Audi A6 Radiator: The Part That Keeps Everything Else From Cooking

Few parts get less attention than this one, but on the Audi A6, a neglected cooling system is behind the vast majority of avoidable serious engine failures. Noticing the early warning signs costs nothing and can save a genuinely large repair bill down the line.

Before you buy: radiator size and design vary significantly by engine size, transmission type, and whether your car has air conditioning. Always confirm against your VIN before ordering.

Audi A6 Radiator: What It Does

On the Audi A6, coolant runs through the radiator to shed engine heat into the airflow, keeping temperatures in check. On many automatics, a separate internal circuit inside the same unit also cools the transmission fluid — one more reason a mismatched part number causes more than just a cooling problem.

Audi A6 Radiator: Watch: Replacing It

🎬 Watch: 2012 Audi A6 (C7) center lower radiator replacement

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C7 main (lower centre) radiator swap

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A Genuinely Useful Piece of Context Worth Knowing About Water Pump Issues — Audi A6 Radiator

If you're facing a coolant leak or overheating concern, this is genuinely worth knowing: related Audi models have had confirmed recalls addressing water pump issues that could cause coolant to leak from the pump housing, with problems on this platform documented occurring anywhere from 30,000 to 70,000 miles.

A genuinely useful, real diagnostic technique worth trying: with the engine cold, removing the coolant bottle cap and having someone rev the engine while you watch the return hose is a simple way to confirm the water pump is genuinely circulating coolant properly.

It's also genuinely worth knowing an important clarification: genuine overheating caused directly by a failed water pump is actually quite rare, more often stemming from warped cylinder heads or a weakened head gasket left over from a previous overheating event.

Audi A6 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.