Parts for your 2016 Toyota Vitz|yaris-Temperature sensors

2016 Toyota Vitz/Yaris Temperature Sensors — Purpose, Care, and When to Replace

Temperature sensors are absolutely fitted to the 2016 Toyota Vitz/Yaris and are central to how the engine and climate systems behave. Technical sources back this up: the Toyota Repair Manual for the 1NR‑FE/1NZ‑FE engines lists an Engine Coolant Temperature (ECT) sensor and an Intake Air Temperature (IAT) sensor, Toyota’s Electrical Wiring Diagram shows the corresponding circuits, and Toyota Techstream’s Data List displays live PIDs for “Coolant Temp” and “Intake Air Temp”. Fault coverage in OBD‑II (DTCs P0115–P0119 for ECT, P0110–P0114 for IAT) further confirms their presence. Toyota’s parts catalogues also list replacement ECT and IAT sensors for this model range.

On a 2016 Vitz/Yaris, the ECT sensor tells the ECU how hot the coolant is so it can sort cold starts, fuelling, ignition timing, radiator fan control, and the dash gauge. The IAT sensor (often built into the MAF sensor on these engines) reports the temperature of the air coming in, which helps the ECU fine‑tune mixtures and emissions. Many variants also carry an ambient temp sensor for the A/C and display.

There’s no scheduled replacement for these sensors, they’re serviced on condition. Good practice during regular servicing includes:

• Scan check: With the engine cold, ECT and IAT should read close to outside temperature. A huge mismatch points to a sensor or wiring issue.
• Cooling system care: Use Toyota Super Long Life Coolant (pink). Old or contaminated coolant can corrode sensor tips and cause flaky readings.
• Connector inspection: Look for green corrosion, loose pins, or oil/coolant wicking into looms.
• MAF/IAT cleanliness: If IAT is in the MAF, clean only with proper MAF cleaner. Don’t touch the element.

Common symptoms of a dodgy ECT/IAT include hard cold starts, rich running, the radiator fan running at odd times, poor fuel economy, or a check‑engine light with the codes above.

Replacing the ECT sensor is straightforward: let the engine cool, relieve system pressure, drain a little coolant, swap the sensor and sealing washer, reconnect the plug, then refill and bleed the cooling system with the heater on. Tighten to the service manual’s spec—overtightening can crack the housing. Afterward, clear any codes and verify readings and fan operation with a scan tool. If replacing an IAT that’s integrated into the MAF, the whole MAF assembly is typically changed.

• Where is the coolant temperature sensor on a 2016 Vitz/Yaris?
  It’s threaded into the engine coolant passage, usually near the thermostat housing on the cylinder head. The plug faces outward for easy access. On some engines, it sits just below the upper radiator hose outlet on the head. A quick look from the top with a torch generally spots it.
• What are the signs the ECT or IAT sensor is failing?
  Expect hard cold starts, rich or lean running, poor fuel economy, the radiator fan stuck on or off, temperature gauge misbehaviour, and a check‑engine light. Scan tool data that’s unrealistic (for example, –40°C or 130°C when cold) is a giveaway. Codes P0115–P0119 (ECT) or P0110–P0114 (IAT) often appear.
• Do these sensors need regular replacement?
  Not routinely. They’re replaced when faulty. Keeping the correct Toyota pink coolant fresh and connectors clean helps them last. When replacement is needed, parts are affordable and labour is modest—ECT typically under an hour, plus coolant top‑up and bleeding.