Parts for your 2007 Toyota Vitz|yaris-Temperature sensors

2007 Toyota Vitz/Yaris temperature sensors: what they do and when to replace them

Based on Toyota’s own technical literature for the XP90 platform (2005–2011) — including the Toyota Repair Manual (Engine Control – SFI System) and the Electrical Wiring Diagram (EWD) — the 2007 Toyota Vitz/Yaris is fitted with multiple temperature sensors. Key among them are the Engine Coolant Temperature (ECT) sensor and the Intake Air Temperature (IAT) sensor, some trims also include ambient and A/C-related temperature sensors. These sources make it clear the sensors are essential for fuel control, ignition timing, fan operation, and gauge display.

On this model, the temperature sensors do plenty of heavy lifting. The ECT sensor is a thermistor threaded into the coolant passage, it constantly feeds the ECU a signal about engine warmth so the car can tweak fuelling and timing on the fly. Cold start enrichment, idle speed, and when the radiator fan kicks on — they all lean on ECT data. The IAT sensor helps the ECU correct for air density, smoothing drivability and helping fuel economy. If optioned, ambient and A/C evaporator/solar sensors handle climate control behaviour.

There’s no fixed service interval for these sensors, but they’re worth a check any time there’s a cooling system job or a Check Engine light. Common symptoms of a crook ECT/IAT include hard cold starts, rich running, higher fuel use, rough idle, the fan running all the time, or a dead temp gauge. Fault codes often seen are P0115–P0119 (ECT) and P0110–P0114 (IAT).

Good servicing habits for the 2007 Vitz/Yaris temperature sensors include:

• Inspect the connector and wiring under the bonnet for corrosion, broken clips, or coolant contamination.
• If diagnosing, compare the sensor’s resistance to the Toyota spec at cold and at operating temp (from the Repair Manual).
• Keep coolant fresh and at the right mix, old or contaminated coolant can attack sensors and housings.
• Use quality OEM-equivalent sensors, cheapies can read off and waste fuel.

Replacing the ECT sensor is a straightforward job for a competent DIYer: let the engine cool fully, relieve pressure, drain a little coolant, unplug the connector, crack the sensor with the right spanner or socket, swap it with a new sealing washer as required, and refit to the specified torque from the Toyota manual. Top up with Toyota Super Long Life Coolant, bleed out air, and verify the gauge and scan-tool readings match reality as the engine warms. Workshops typically bundle this with cooling system service so the bleed is done right and any thermostat or hose issues get sorted at the same time.

Referencing: Toyota Yaris/Vitz (XP90) Repair Manual – Engine Control (SFI), Cooling, and Instrumentation sections, Toyota Electrical Wiring Diagram (EWD) for 2007 Yaris/Vitz, Toyota Technical Information System (TIS) service documentation.

Popular questions about 2007 Toyota Vitz/Yaris temperature sensors

Where is the engine coolant temperature (ECT) sensor located on a 2007 Vitz/Yaris?

On most 1NZ-FE engines used in the 2007 Vitz/Yaris, the ECT sensor is threaded into the water outlet/thermostat housing near the upper radiator hose connection. It’s accessible under the bonnet with simple hand tools. Other engines in the range have a similar spot on the coolant passage. A quick look in the Toyota EWD/Repair Manual will confirm the exact location for your engine code.

Can a faulty temperature sensor cause high fuel use or rough running?

Yes. If the ECT reads “permanently cold”, the ECU enriches the mixture and can hold a higher idle, chewing through fuel and washing the cylinders. If the IAT reads wrong, fuel trims and timing can drift, causing hesitation or a doughy throttle. Expect a Check Engine light with codes like P0115–P0119 or P0110–P0114 when things get bad enough.

Do I need to bleed the cooling system after replacing the ECT sensor?

Absolutely. Any time the cooling system is opened, air can be trapped. Refill with the correct Toyota SLLC premix, run the engine with the heater on, squeeze the upper hose to purge air, and top up the radiator and overflow as needed. Watch the temp gauge and verify fan operation and stable scan-tool temperature as it reaches operating temp.