Parts for your 2017 Toyota Vitz|yaris-Radiator cap

2017 Toyota Vitz/Yaris radiator cap — is there one?

Short answer: there isn’t a traditional radiator-mounted cap on the 2017 Toyota Vitz/Yaris. Toyota’s repair literature for the XP130-series Vitz/Yaris (2014–2019) cooling system shows a sealed radiator without a filler neck, the pressure cap lives on the remote coolant reservoir (also called the degas or surge tank). This layout is confirmed across Toyota’s TIS repair manuals (Cooling System section for 1KR-FE/1NR-FE/1NZ-FE/1NZ-FXE engines), the Toyota Electronic Parts Catalogue (radiator assembly lists no cap, the cap is specified with the reservoir), and owner’s manuals that identify the reservoir cap as the service fill point and warn against opening it when hot. Third-party references like Haynes for Yaris 2011–2019 also describe the pressurised expansion tank setup.

Why Toyota doesn’t use a radiator cap here comes down to packaging, reliability, and air management. By moving the pressure cap to a higher-mounted, pressurised reservoir, the system is easier to fill and bleed, reduces trapped air in the engine, and allows the radiator to sit lower behind the bumper for better packaging and crash performance. It also means there’s a single, clearly marked service point under the bonnet, instead of a separate radiator neck.

If someone’s chasing a “radiator cap” for this model, what they actually need is the coolant reservoir pressure cap. It’s the bit that holds system pressure (typically around 1.1 bar) and controls coolant flow to and from the bottle as temperatures change. During servicing, it’s smart to:

• Inspect the reservoir cap’s seal for cracks, flattening, or stickiness.
• Check the spring action, a tired spring can cause boiling, hard hoses, or slow heater performance.
• Replace the cap if there’s any doubt—caps are inexpensive and can prevent overheating dramas.
• Top up/replace with Toyota Super Long Life Coolant (pink) as specified, and only open the cap when the engine is fully cool.

Bottom line: there’s no cap on the radiator itself, but there is a vital pressure cap on the reservoir that deserves the same attention in regular servicing.

Popular questions

Where is the radiator cap on a 2017 Toyota Vitz/Yaris?
On this model the radiator doesn’t have a cap. The pressure cap is on the plastic coolant reservoir (degas tank) mounted high in the engine bay. That’s the only cap you’ll open for filling or bleeding—only when the engine is cold.

What pressure rating is the coolant cap, and does it matter?
Most genuine caps for this model are around 1.1 bar (110 kPa). Using the correct rating matters: too low and the engine may run hot or boil, too high and hoses or the reservoir can cop extra stress. Stick with a genuine or high-quality equivalent that matches the spec.

When should the reservoir cap be replaced?
There’s no fixed kilometre interval, but if you notice coolant loss with no leaks, swelling hoses, overheating under load, or a perished seal on the cap, replace it. Many techs swap the cap as cheap insurance when doing a coolant flush.