Parts for your 2018 Toyota Wish-Temperature sensors

2018 Toyota Wish temperature sensors — what they do and how to look after them

Based on Toyota technical literature, temperature sensors are absolutely fitted to the Toyota Wish platform used through 2017–2018 registrations. Toyota’s Repair Manual for the ZGE2# series (2ZR-FAE/3ZR-FAE engines) and New Car Features documentation describe the Engine Coolant Temperature (ECT) sensor and Intake Air Temperature (IAT) sensor as part of the SFI engine control. The Toyota A/C service manual also details ambient air and evaporator temperature sensors for HVAC operation. Common Toyota OBD-II diagnostics for this model family include ECT codes P0115–P0119 and IAT codes P0110–P0113, further confirming use of these sensors.

On a 2018 Toyota Wish, temperature sensors help the ECU and HVAC do their jobs properly. The ECT sensor tells the engine computer how hot the coolant is so it can set the fuel mix, ignition timing, cold-start enrichment and radiator fan operation. The IAT sensor reports how warm the incoming air is, which affects air density and fuel delivery. The transmission temperature sensor (auto models) helps the TCM protect the gearbox and manage shift quality. Upfront, the ambient and evaporator sensors let the climate control hold a steady cabin temp without fogging or icing.

• Engine Coolant Temperature (ECT): typically at the water outlet/thermostat housing.
• Intake Air Temperature (IAT): often integrated into the MAF on many ZGE2# variants.
• Automatic Transmission Fluid (ATF) temperature: inside the transmission.
• Ambient and evaporator temperature: for A/C performance and demist.

There’s no routine replacement interval for these sensors, they’re serviced as needed. During regular servicing, it’s smart to scan live data on a cold start and at operating temp — the ECT should track coolant warm-up smoothly to roughly 85–95 °C, and IAT should be close to ambient with the engine off. Any wild readings, hard cold starts, rough idle, poor fuel economy, radiator fans running all the time, or odd A/C behaviour are cues to test further.

Replacement tips? Use quality OEM-equivalent parts, fit a new sealing washer or O-ring where specified, and avoid over-tightening. Let the engine go stone cold before touching coolant sensors, catch and top up Toyota Super Long Life coolant, and bleed air properly. For IATs integrated into the MAF, clean only with MAF-safe cleaner — no harsh sprays. Check connectors for corrosion and broken locks, as many “sensor faults” are actually wiring or plug issues. With a scan tool, clear codes and confirm normal readings on a road test. Most Wish owners find these are quick, cost-effective fixes that restore smooth running and keep the car happy through big kilometres across Aus and NZ.

Popular questions

How can someone tell if the coolant temperature sensor on a Toyota Wish is failing?
Typical signs include hard cold starts, black smoke or rich running, fans running constantly, a lazy temp gauge, or DTCs like P0115–P0119. A scan tool will show an implausible coolant reading (e.g., stuck very low or very high). Comparing the sensor value to actual ambient on a cold engine is a quick check — they should match within a couple of degrees.

Is the IAT sensor separate or built into the MAF on the Wish?
On many ZGE2# Wish variants the IAT is integrated into the MAF sensor. Some market versions may use a separate IAT in the intake duct. Under the bonnet, a 5‑pin MAF is a good hint the IAT is built in. If separate, you’ll see a small additional sensor boss on the air duct upstream of the throttle.

Should the ECT sensor be replaced during cooling system jobs?
It’s not mandatory, but when doing a thermostat or water outlet, access is easy. If the car’s got high kilometres or there’s any history of odd temp readings, preventive replacement with a quality sensor while the coolant’s already drained can save time later.