Lexus CT200h Radiator: Specs, Fitment & Common Faults

A genuinely important finding: this hybrid has a separate inverter coolant system, and if it detects overheating, the car likely won't let you continue driving at all — a protective measure that may mean towing.

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OEM Part Number: 1640037230 (as quoted in catalogue listings — confirm via VIN) — aftermarket radiators Nissens 646842 / Denso DRM50076

Accuracy note: Covers the Lexus CT200h (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 646842 (600 x 368 x 16 mm, aluminium soldered fins, plastic tanks, supplied with seals); cross-refs Denso DRM50076, Valeo 701657 / 701176, NRF 53926, Van Wezel 53002608, Mahle CR 1901 000S, Hella 8MK 366 300-361, Prasco TY352R005.
Core sizes & variants	One 16 mm core covers every CT 200h
Genuine (OE) numbers quoted	1640037230; 1640037260; 1640037240; 164000T240; 164000T250 (Toyota / Lexus)
Fitment notes	Inlet 34 mm, outlet 35 mm; gaskets are in the box.

Accuracy note: genuinely worth knowing: coolant capacity and radiator sizing on the CT200h tend to track engine displacement and power output closely — a part correct for a smaller-engined version of the same model can undersize the cooling for a larger-engined one.

Lexus CT200h Radiator: The Part That Keeps Everything Else From Cooking

Unglamorous as it is, the Lexus CT200h'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.

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.

Lexus CT200h Radiator: What It Does

On the Lexus CT200h, 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.

Lexus CT200h Radiator: Watch: Replacing It

🎬 Watch: Radiator replacement 2013 Lexus CT200h

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Garage video; alt https://www.youtube.com/watch?v=nLCTMJj7X54 (11 CT200h)

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A Genuinely Important Finding Worth Knowing About This Hybrid's Cooling System — Lexus CT200h Radiator

This is genuinely important to understand: there's a genuinely separate inverter coolant system, distinct from the normal engine cooling system, specifically to keep the power electronics at a safe temperature. It's also genuinely important to know that if the hybrid system detects an overheat, it will likely not allow you to continue driving at all, as a protective measure specifically for the transmission, electric motors, and high-voltage battery — the car may genuinely need to be towed rather than driven even a short distance.

A genuinely useful, emergency-only tip worth knowing: if the inverter coolant level specifically is found low in a genuine emergency, temporarily topping it off with plain water rather than proper coolant can get you safely to your destination, with a proper inspection and refill to follow once there.

It's also genuinely worth knowing that diagnosing the exact cause of a hybrid overheat warning is genuinely difficult without a proper scan tool, since retrieving the actual fault codes is necessary to identify which specific component has failed. It's also worth always properly diluting coolant concentrate with distilled water per the bottle's instructions, since undiluted coolant can itself cause overheating.

Lexus CT200h 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 Lexus Radiator

The same part, covered across other Lexus models.