Parts for your 2009 Toyota Wish-Temperature sensors

2009 Toyota Wish temperature sensors: what they do and how to look after them

Technical sources confirm the 2009 Toyota Wish definitely uses temperature sensors. Toyota’s New Car Features (ZGE20/25 series, 2009–), the Toyota Repair Manual (RM), and the Electrical Wiring Diagram (EWD) list several: the engine coolant temperature (ECT) sensor on the 2ZR-FAE/3ZR-FAE engines (and earlier 1ZZ/2AZ in late first-gen 2009 builds), the intake air temperature (IAT) sensor, the ambient and evaporator temperature sensors for the climate control system, and the transmission fluid temperature sensor in the CVT (K311 family). These sensors feed the engine ECU, A/C amplifier, and transmission control to keep the Wish running sweet as.

In day-to-day driving, temperature sensors help the ECU trim fuel and ignition timing, set idle speed on cold starts, engage radiator fans, and manage CVT line pressure and shift strategy. For the cabin, they make the auto A/C behave properly, stopping the evaporator from icing up and keeping the cabin temp consistent on those muggy summer arvos.

When it comes to servicing, most temperature sensors are “fit and forget” but they still benefit from basic checks:

• At each major service (every 20,000 km or annually), scan live data with Techstream or a quality scan tool. Look for realistic values: coolant temp should rise smoothly to about 85–95 °C, IAT should track close to ambient when cold, and CVT temp should climb progressively with driving.
• Inspect connectors for corrosion or coolant wicking at the ECT. A green crusty plug or dampness under the bonnet near the thermostat housing is a red flag.
• If the cooling system has had a leak or an overheat, test the ECT and radiator fan operation once refilled and bled. Air pockets can fool the sensor and cause erratic fan cycling.
• For A/C complaints (poor cooling, cycling, or foggy vents), check the evaporator and ambient temp sensors via the A/C self-diagnosis and live data before gassing the system.

Replacement is straightforward for most sensors. The ECT typically threads into the housing, wait for a stone-cold engine, relieve pressure, and top up with the correct Toyota SLLC coolant after refit. IAT sensors often sit in the MAF housing—replace the sensor or the entire MAF as specified in the RM. CVT temperature sensors are internal, if there’s a temp-related fault, confirm wiring and fluid condition first, as many DTCs stem from degraded ATF rather than a failed sensor. Always clear codes and verify with a proper road test and live data.

Genuine or high-quality OEM-equivalent parts from DENSO and Toyota are recommended—their characteristics match the calibration in the Wish’s control modules, which keeps fuel economy and drivability on point.

Popular questions about 2009 Toyota Wish temperature sensors

Where is the engine coolant temperature sensor located on a 2009 Toyota Wish?

On most 2009 Wish models, the ECT sensor is threaded into the thermostat housing or coolant outlet on the cylinder head, facing the radiator side. It’s a two-pin connector. Access is under the bonnet from above, some models benefit from removing the intake ducting for room.

If the vehicle is an early 2009 first-gen build, the position is similar—still at the coolant outlet—so the approach remains the same.

What are the symptoms of a failing temperature sensor in a 2009 Wish?

Common clues include hard cold starts, high idle that lingers, rich fuel smell, poor fuel economy, radiator fans running at odd times, or a temp gauge that behaves strangely. The A/C may cycle or fail to cool properly if the ambient or evaporator sensor is off.

Scan data that shows implausible readings—like minus figures on a warm day or sudden spikes—usually confirms it.

Does the CVT in the 2009 Wish have a temperature sensor, and does it need routine replacement?

Yes, the K311-series CVT uses an internal fluid temperature sensor for pressure control and protection. It’s not a routine replacement item. Focus on clean, correct-spec CVT fluid and cooling system health.

Only consider sensor diagnosis after confirming fluid condition, wiring integrity, and any relevant DTCs with a proper scan tool.