Volkswagen Up! Radiator: Specs, Fitment & Common Faults

If your Up! has a TSI turbo engine, VW has legally admitted to using "inferior thermoplastic materials" in the water pump housing — a real class-action settlement covers this.

Illustration for editorial purposes

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OEM Part Number: 1S0121253AC (as quoted in catalogue listings — confirm via VIN) — aftermarket radiators Nissens 65300 / Valeo 701128

Accuracy note: Covers the Volkswagen Up! (2011-) 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 65300 (352 x 360 x 23 mm, aluminium core with plastic tanks, fits 1.0 60 PS CHYA/DAFA and, with its Mii and Citigo sisters, the 1.0 75 PS CHYB and 1.0 EcoFuel CPGA); Nissens 606239 (588 x 257 x 26 mm, aluminium core with plastic tanks, fits 1.0 TSI 90 CHZA/DKLC and 1.0 GTI 115 DKRA); Valeo 701128; Denso DRM32036; Mahle CR 831 000S; NRF 53102 and 53101; Van Wezel 58002325 and 58012725; Hella 8MK 366 301-701
Core sizes & variants	The normally aspirated 1.0 MPI engines take the small 352 x 360 mm radiator, which is also used by the Seat Mii, Skoda Citigo and the electric e-Up/e-Citigo. The turbocharged 1.0 TSI and GTI take a much wider 588 x 257 mm radiator (OE 1S0121253AC) that is unique to the turbo cars.
Genuine (OE) numbers quoted	1S0121253AC (TSI/GTI); MPI radiator OE number not quoted
Fitment notes	The MPI radiator comes with gaskets and seals and has 32 mm connections; the TSI/GTI unit has 32.5 mm connections. Check for the turbo before ordering, as the two are not interchangeable.

Accuracy note: genuinely worth knowing: radiator core size and construction can differ between petrol and diesel Up! engines, and again between manual and automatic gearboxes where the automatic needs an integrated oil cooler circuit — confirm your exact engine code and transmission before ordering.

Confirmed: A Genuinely Serious, Class-Action-Level Design Flaw on TSI Engines — Volkswagen Up! Radiator

If your car has a TSI turbo petrol engine (particularly the EA888 family used across much of VW's range from around 2015 onward), this is genuinely the single most important thing to know before anything else on this page. The water pump and thermostat are combined into one integrated plastic housing, and this plastic becomes brittle and develops hairline cracks after thousands of ordinary heat cycles — leading to a coolant leak that's often difficult to spot at first. This isn't a minor manufacturing quirk: VW has confirmed through legal documents that "inferior thermoplastic materials were used" in these water pump components, and the issue has been the subject of multiple class-action lawsuits.

What VW's settlement genuinely offers: a Technical Service Bulletin extends the warranty on this specific part to 8 years/80,000 miles, and the class-action settlement goes further still — up to 10 years/100,000 miles warranty, reimbursement of qualifying repairs, and crucially, reimbursement of up to £3,300 for consequential damage if the leak went undiagnosed long enough to damage the turbocharger or EGR system. If you've paid for this repair or suffered related engine damage, it's genuinely worth checking whether you qualify before assuming the cost is yours to bear.

Watch for a low coolant warning, a sweet smell in the engine bay (especially after motorway driving), or fault codes P00B7, P2681, P1889, or P0128 — any of these are worth investigating immediately rather than topping up and continuing, since this failure can escalate from a slow leak to sudden, severe overheating within minutes. If this does need replacing, the entire water pump and thermostat housing assembly must be replaced together — never just one part of it.

Volkswagen Up! Radiator: The Part That Keeps Everything Else From Cooking

This isn't a part anyone gets excited about, but on the Volkswagen Up!, overlooked cooling problems are responsible for most serious engine failures that aren't simple wear-and-tear. Catching the early symptoms is about the cheapest insurance available against a major bill later.

Volkswagen Up! Radiator: Watch: Replacing It

🎬 Watch: VW Up 2018 Radiator Replacement Tutorial

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German alternative FHoKBjoBPwA (2012 Up rusted radiator)

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.

Volkswagen Up! Radiator: What It Does

Keeping the Volkswagen Up!'s engine temperature within safe limits comes down to the radiator's job of transferring heat from the coolant into the surrounding air. Automatic-gearbox versions often build in a second circuit for transmission fluid cooling too, which is exactly why fitting the wrong part number can cause two problems, not one.

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Volkswagen Up! 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 Volkswagen Radiator

The same part, covered across other Volkswagen models.