Parts for your 2015 Toyota Vitz|yaris-Thermostat

2015 Toyota Vitz/Yaris Thermostat — what it does and when to replace it

Yes, a thermostat is absolutely fitted to the 2015 Toyota Vitz/Yaris (XP130 series). This applies across common engines like the 1KR‑FE 1.0L, 1NR‑FE 1.3L and 1NZ‑FE 1.5L. Toyota’s Repair Manual for Yaris/Vitz (NCP13#/KSP130 series) covers a specific “Cooling – Thermostat” procedure, and the Toyota Electronic Parts Catalogue lists a thermostat or thermostat-with-housing (water inlet sub-assembly) for these engines. Aftermarket workshop manuals (e.g., Haynes for 2010–2017 Yaris) also include thermostat testing and replacement for this generation. So it’s a relevant, serviceable part on the 2015 Vitz/Yaris.

• Toyota Repair Manual (Yaris/Vitz NCP13#/KSP130, Cooling – Thermostat)
• Toyota Electronic Parts Catalogue (Thermostat / Water Inlet sub-assembly for 1KR‑FE, 1NR‑FE, 1NZ‑FE)
• Haynes Toyota Yaris 2010–2017 (Cooling system service and thermostat replacement)

The thermostat’s job is to help the engine warm up quickly, then keep it right on its sweet-spot temperature. It stays closed when the engine’s cold so coolant circulates within the block, then opens at a set temperature to let coolant flow through the radiator. That means better fuel economy, steadier cabin heat, lower emissions and a happier engine under the bonnet on those long Kiwi and Aussie kilometres. On the 2015 Vitz/Yaris, the thermostat sits in the water inlet housing on the engine—location and shape vary a touch by engine code, but the principle is the same.

It’s not a scheduled replacement item, but it’s smart to check it whenever the cooling system is being serviced or the coolant is changed. Telltales of a crook thermostat include slow warm‑up, running too cool (often with a P0128 fault), overheating, fluctuating temp gauge, weak heater output, or fans running more than they should. If any of that shows up, replace the thermostat and its O‑ring/gasket as a set.

Best practice when replacing it: use quality OEM‑spec parts, fit the jiggle valve at the prescribed clock position (usually near top), torque the housing bolts correctly, and refill with Toyota Super Long Life Coolant (pink, premix) or equivalent. Bleed air carefully—heater on full hot, squeeze the upper hose, top up after cool‑down—and check for weeps around the housing. It’s a tidy job to pair with a coolant change. While you’re there, inspect the radiator cap, hoses and water pump for signs of age. On high‑mileage cars, a preventative thermostat swap during major cooling service can save hassles down the road, especially if the car sees lots of short trips or hot summer traffic.

• Common symptoms: slow warm-up, temp gauge hunting, heater lukewarm, P0128, or visible leaks at the housing.
• Handy tip: plan 1–2 hours, have a drain pan ready, and don’t reuse a flattened O‑ring.

What temperature rating does the 2015 Vitz/Yaris thermostat use?

Most engines in this range use a thermostat that starts opening in the low‑to‑mid 80s °C and is fully open by the low‑90s °C. Exact specs vary by engine code (1KR‑FE, 1NR‑FE, 1NZ‑FE) and market. If in doubt, check the stamping on the replacement thermostat or the service data for the specific engine.

How often should the thermostat be replaced?

There’s no fixed interval—it’s replaced when faulty or during major cooling work. Many owners keep the original until symptoms appear. If you’re doing a big cooling refresh (hoses, pump, radiator) or the car has high kilometres, a new thermostat with fresh coolant is sensible insurance. Follow the coolant interval appropriate to your market and Toyota SLLC use.

Where is the thermostat located on the 2015 Vitz/Yaris?

It’s mounted in the water inlet housing on the engine block. Access and orientation differ slightly by engine: on the 1NR‑FE and 1KR‑FE it’s near the front of the engine, low to mid height, behind the radiator fans, on the 1NZ‑FE 1.5L it’s at the block’s water inlet. Look for the lower radiator hose—trace it to the housing that holds the thermostat.