Parts for your 2006 Toyota Vitz|yaris-Radiator cap

2006 Toyota Vitz/Yaris radiator cap — what it is and why it matters

Based on Toyota’s factory documentation and parts listings, the 2006 Toyota Vitz/Yaris (XP90 series: SCP90/NCP90/NCP91) uses a pressurised radiator cap mounted on the radiator itself. Technical sources: Toyota Repair Manual for 2005–2010 Yaris/Vitz (Cooling System section specifies a radiator cap with an opening pressure around 108 kPa/1.1 bar), Toyota Electronic Parts Catalogue (Group 16 – Cooling, lists a “Cap, Radiator” for XP90), and aftermarket catalogues from major radiator suppliers that identify the XP90 radiator as a cap-type unit. So yes, a radiator cap is fitted and relevant on this model.

For the 2006 Vitz/Yaris, the radiator cap does more than just seal the top of the radiator. It holds pressure (typically 108 kPa/1.1 bar) so the coolant’s boiling point is raised, helping the engine keep its cool even on a scorching Aussie or Kiwi summer’s day. The cap also has a vacuum valve that lets coolant return from the overflow bottle back into the radiator as things cool down, keeping the system topped up without letting air sneak in.

As part of regular servicing, it’s smart to give the cap a look at every oil change and test or replace it at coolant service intervals. Small money, big peace of mind. If the spring weakens or the rubber seals harden, the system can’t hold pressure, which can show up as random overheating, gurgling in the heater core, or a reservoir that overflows and then runs dry.

• Typical signs a cap is due: unexplained coolant loss, collapsed upper hose after cool-down, crusty deposits on the cap seat, cracked or flattened seals, or a sweet smell under the bonnet.
• When replacing: match the pressure rating (1.1 bar/108 kPa is the usual spec for XP90), choose a quality cap, and only open the system stone cold. Twist slowly with a rag in case there’s residual pressure.
• Good practice: pressure-test the cap during coolant changes, renew the cap every 4–5 years or around 80–100,000 km, and use the correct Toyota Super Long Life Coolant (pink) or equivalent meeting the same spec.

Location-wise, owners will find the cap on the radiator neck, with a separate overflow reservoir nearby. Hand-tight is all that’s needed, don’t lean on it with a tool. If the old cap looks iffy or fails a pressure test, tossing a new one on is cheap insurance for the Yaris’s cooling health.

Popular question: What pressure radiator cap does a 2006 Toyota Vitz/Yaris use?

The XP90 typically uses a 1.1 bar (108 kPa) radiator cap.

That rating keeps the coolant’s boiling point safely higher.

Some markets may list the spec as 108–118 kPa in test ranges.

Always match or follow the label on the original cap if present.

Using a lower rating can invite boil-over on hot days.

Using a higher rating can stress hoses and the radiator.

A quality OEM-equivalent cap is the safe choice.

Check the cap’s gasket style matches the radiator neck.

Parts catalogues for XP90 confirm a pressurised radiator cap.

Your service manual lists the test pressure spec as guidance.

Work only on a cold engine before removing the cap.

If unsure, ask a parts pro to cross-check by VIN.

Popular question: How do you know the radiator cap needs replacing on a 2006 Yaris?

Coolant mysteriously disappears, but no obvious leaks are seen.

The overflow bottle keeps filling up and doesn’t draw back down.

The upper radiator hose collapses flat after the engine cools.

You notice overheating at highway speeds or on long climbs.

There’s a sweet coolant smell around the front of the car.

You can see cracked or perished rubber on the cap seal.

White or rusty crust forms where the cap meets the neck.

A pressure test shows it opens below the rated 1.1 bar.

The cabin heater gurgles or blows lukewarm at idle.

There are air bubbles returning to the overflow when hot.

The cap feels loose or doesn’t click/lock positively.

It’s five-plus years old and never been tested or changed.