Parts for your 2008 Toyota Vitz|yaris-Temperature sensors

2008 Toyota Vitz/Yaris temperature sensors — what they do and how to look after them

Based on technical literature, temperature sensors are absolutely fitted to the 2008 Toyota Vitz/Yaris (XP90). Toyota’s Repair Manual for the Yaris (Engine Control System, 1NZ-FE/2NZ-FE) details the Engine Coolant Temperature (ECT) sensor and its diagnostics (DTCs P0115–P0119, P0125). The 2008 Yaris Electrical Wiring Diagram (EWD) shows the ECT circuit to the ECM and radiator fan control, while parts catalogues list both an ECT sensor and an Intake Air Temperature (IAT) sensor—on most models the IAT is integrated into the Mass Air Flow (MAF) sensor. Aftermarket manuals (e.g., Toyota Yaris 2006–2011 workshop guides) also cover testing and replacement of these sensors. So yes, temperature sensors are used on this vehicle.

On the 2008 Vitz/Yaris, temperature sensors play a quiet but critical role in how the car runs day to day. The ECT sensor tracks coolant temperature so the engine computer can sort cold-start enrichment, idle speed, ignition timing, and when to kick the radiator fans on. An IAT sensor keeps tabs on incoming air temp to fine-tune fuel delivery. Many cars also have an ambient air sensor for the HVAC/outside temp display, and autos may monitor transmission fluid temperature.

There’s no fixed replacement interval for these sensors, but they’re worth a look during regular servicing, especially if there are signs of drama such as rough cold starts, high idle, poor fuel economy, the temp gauge acting odd, fans running all the time, or a check engine light with codes like P0115–P0119 or P0125.

• Location: The ECT sensor is typically on the water outlet/thermostat housing at the cylinder head end. The IAT is usually built into the MAF sensor on the intake tube.
• Quick checks: Scan live data (ECT and IAT) from cold to hot—temps should climb smoothly. Compare ECT to ambient when stone cold