Citroen C1 Radiator: Specs, Fitment & Common Faults

On the C1, a genuinely specific detail before DIY thermostat housing work: real torque figures that prevent over-tightening from causing the exact leak you're trying to fix.

Illustration for editorial purposes

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OEM Part Number: 1611668880 (as quoted in catalogue listings — confirm via VIN) — aftermarket radiators Nissens 64685 / Valeo 735072

Accuracy note: Covers the Citroen C1 (2014-) 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 64685 (375 x 328 x 16 mm, soldered aluminium core with plastic tanks, fits 1.0 VTi 68 and 1.0 VTi 72, engine code CFB / 1KR); Valeo 735072; Denso DRM21602 / DRM21600; Mahle CR 1114 000P / CR 998 000P; NRF 53459; Van Wezel 53002363 / 53002360; Ava TO2360 / TOA2360; Hella 8MK 366 302-821
Core sizes & variants	One radiator covers every C1 II, and the same part also fits the first-generation C1 (2005-2014), Peugeot 107 and 108 and Toyota Aygo (B1 and B4). All are 1.0 three-cylinder petrols, so there is no petrol/diesel split.
Genuine (OE) numbers quoted	1611668880; 1330P5; 1330P4; 164000Q010 (Citroen/Peugeot/Toyota); 1333C4; 1333C5 (Peugeot)
Fitment notes	Both connections are 28 mm; supplied with seals but without the expansion tank or cap.

Accuracy note: genuinely worth knowing: whether a C1 has air conditioning or a larger optional engine can change radiator sizing on some variants — fitment guides that only ask for model and year can still get this wrong, so cross-check the engine code where possible.

A Genuinely Specific Detail Worth Knowing Before DIY Thermostat Housing Work — Citroen C1 Radiator

If you're replacing the thermostat housing yourself, it's genuinely worth knowing a specific detail that catches many DIYers out: on several engines in this range, the housing is secured directly onto the cylinder head with a thin bead of RTV sealant rather than a conventional gasket, using a relatively large number of bolts (commonly 8) tightened to a comparatively light torque figure — documented at around 8Nm on some engines — rather than fewer bolts at high clamping force. Over-tightening these bolts, assuming a higher torque figure "seems safer," can actually crack the housing or distort its sealing surface, causing exactly the leak you were trying to fix. Confirming the genuine torque specification and sealing method for your specific engine before starting is worth doing rather than guessing.

A genuinely distinct leak point worth checking separately: the corrugated rubber pipe connecting the water pump to the thermostat housing, which runs behind the engine, is a separate, well-documented leak point in its own right — distinct from the housing or pump themselves. If you've replaced the housing and pump but coolant is still disappearing, this specific pipe is worth checking directly before assuming a more complex fault.

It's also worth knowing that a genuine air lock trapped in the system after any coolant work is a common cause of the same overheating symptoms as a faulty thermostat or pump — always follow the correct bleeding procedure for your specific engine after any repair in this area.

Citroen C1 Radiator: The Part That Keeps Everything Else From Cooking

It's an unglamorous part, but on the Citroen C1, the cooling system is behind almost every serious non-wear engine failure that could have been prevented. Spotting trouble here early is about as cheap an insurance policy as exists against a genuinely expensive repair bill.

Citroen C1 Radiator: Watch: Replacing It

🎬 Watch: CityBug Radiator Replacement,.. And 5 Snapped Bolts. C1/Aygo/107 Losing Coolant (older gen)

Watch on YouTube ↗

Mk1 C1 (2005-14); same 1KR engine layout as 2014- car, no Mk2-specific video found

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.

Citroen C1 Radiator: What It Does

On the Citroen C1, heat from the engine coolant is shed to the surrounding air through the radiator, keeping engine temperature in a safe range. On automatic gearboxes, it often doubles up, cooling transmission fluid through a separate internal circuit too — which is why getting the exact part number right matters more here than on a simple heat exchanger.

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Citroen C1 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 Citroen Radiator

The same part, covered across other Citroen models.