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, they should be similar.
• Replacement tips: Let the engine cool fully, relieve any cooling system pressure, and disconnect the battery. Swap the ECT sensor with a new sealing washer, torque to the spec in the Toyota manual, then top up with Toyota Super Long Life Coolant (pink) and bleed air from the system. Inspect connectors for corrosion and broken locking tabs.

Good habits under the bonnet go a long way: keep coolant fresh (per Toyota intervals), fix minor leaks promptly, and make sure earths and plugs are clean. A healthy set of sensors helps the little Yaris run sweet, use less petrol, and avoid overheating on long Kiwi and Aussie drives.

FAQs

Where is the engine coolant temperature sensor on a 2008 Toyota Vitz/Yaris?
The ECT sensor sits on or near the thermostat housing/water outlet at the cylinder head end of the engine (1NZ-FE/2NZ-FE). It’s a two‑pin sensor threaded into the coolant passage, accessible from the top with basic hand tools once the intake ducting is moved aside.

What fault codes point to a dodgy temperature sensor?
Common ECT-related DTCs are P0115 (circuit), P0116 (range/performance), P0117 (low input/short to ground), P0118 (high input/open circuit), and P0125 (insufficient coolant temperature for closed loop). An IAT fault may throw P0110–P0114. Always confirm with live data and wiring checks.

Does the 2008 Yaris have more than one temperature sensor?
Yes. It uses an ECT sensor for the engine, an IAT sensor (often built into the MAF), an ambient air temp sensor for HVAC/outside temp display on some trims, and automatic models may monitor transmission fluid temperature in the valve body.