Citroen C4 Radiator: Specs, Fitment & Common Faults

On the C4, 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.

Generation covered: this guide is for the current C4 (launched 2021, facelifted 2024), with particular focus on 2021–2023 registered examples now old enough for parts to be a common search. Check your logbook or VIN if you're unsure which generation you have.

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A Genuinely Specific Detail Worth Knowing Before DIY Thermostat Housing Work

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.

The Part That Keeps Everything Else From Cooking

Nothing about this component is glamorous, but almost every serious engine failure that isn't wear-related traces back to a cooling system problem left unaddressed. Catching the early signs here is genuinely cheap insurance against a much bigger bill.

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.

OEM Part Numbers

Accuracy note: genuinely worth knowing: some C4 engines pair the radiator with an integrated oil cooler or a separate charge-air cooler depending on turbocharging — these aren't interchangeable, so confirm your exact engine spec before ordering.

Radiator specification varies significantly between petrol/mild-hybrid and fully electric ë-C4 versions — the electric version uses an entirely different cooling architecture for its battery and motor rather than a conventional engine radiator. Confirm your exact powertrain before ordering.

What It Does

The radiator transfers heat from the engine coolant to the surrounding air, keeping engine temperature within a safe operating range. On automatic versions, it often also cools transmission fluid through a separate internal circuit — one more reason the correct part number matters so much here.

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.