Parts for your 2021 Toyota C-hr-Radiator cap

2021 Toyota C‑HR radiator cap — what it does and when to replace it

Based on Toyota’s technical sources, the 2021 Toyota C‑HR does use a radiator cap — it’s a pressure cap mounted on the pressurised coolant reservoir (degas bottle), not on the radiator neck. This layout is shown in the Toyota C‑HR Owner’s Manual (Engine coolant, Do‑it‑yourself maintenance), detailed in the Toyota Repair Manual for the C‑HR cooling system, and listed in the Toyota Electronic Parts Catalogue as a “cap sub‑assembly, radiator” for C‑HR (NGX10/ZYX10 series). So yes, a radiator cap is relevant and fitted on this model.

On the C‑HR, the radiator cap’s job is to hold a set pressure in the cooling system so the coolant’s boiling point is raised, helping the engine stay happy on hot Aussie and Kiwi days and during long climbs. When pressure creeps too high, the cap vents a little coolant to the reservoir, as the engine cools, it draws coolant back in. Because the C‑HR uses a pressurised reservoir, the cap you see on that tank is the system’s pressure cap — opening it when hot can cause a scald, so always wait until the engine is completely cool under the bonnet.

Good servicing includes a quick check of the cap. Look for perished rubber seals, cracked plastic, a sticky spring, or white crusty deposits. If the cooling system’s been overfilled, boiled, or hoses are collapsing after shutdown, the cap could be weak. Use Toyota Super Long Life Coolant (pink) of the correct spec, and keep the mix right — the cap and coolant work as a team.

• When to replace: if there are leaks, a weak hold‑pressure on a cap tester, damaged seals, or as preventative maintenance around major cooling‑system services.
• What to fit: a genuine or high‑quality cap that matches the C‑HR’s specified pressure rating (check the marking on the original cap and the service data).
• How to do it: let the car go stone‑cold, cover the cap with a rag, turn slowly to the first detent to bleed any residual pressure, then remove. Wipe the neck, fit the new cap, and seat it fully.

After cap replacement or coolant work, run the engine to operating temperature with the heater on and watch the level at the reservoir. The C‑HR’s degas bottle helps purge air on its own, but topping to the “FULL” mark when cold is the go. If temps climb or fans run constantly, stop and have it checked.

Where is the radiator cap on a 2021 Toyota C‑HR?

It’s on the pressurised coolant reservoir (degas bottle) at the front of the engine bay, not on the radiator itself. That reservoir cap is the system’s pressure cap.

How often should the radiator cap be replaced?

There’s no fixed interval, but it’s smart to test it during cooling‑system services and replace it if seals are tired, the spring’s weak, or after an overheating event. Many owners choose to renew it preventatively when doing coolant at major intervals.

What pressure rating should be used?

Use a cap that matches the factory rating shown on the original cap and in Toyota’s service data for the C‑HR. Sticking with a genuine cap or a quality equivalent that meets the specified kPa/bar rating keeps the system working as designed.