Parts for your 2007 Toyota Highlander-Temperature sensors

2007 Toyota Highlander temperature sensors — what they do and how to look after them

Based on Toyota’s own technical literature, temperature sensors are absolutely fitted to the 2007 Toyota Highlander and are critical to how it runs. The Toyota Repair Manual and the Electrical Wiring Diagram (EWD) for the 2007 Highlander (XU20) outline several temp-sensing devices: the Engine Coolant Temperature (ECT) sensor, Intake Air Temperature (IAT) sensor (often integrated with the MAF), ambient air temperature sensor for the outside-temp/HVAC system, A/C evaporator thermistor, transmission fluid temperature sensor for the automatic gearbox, and (on models with automatic climate control) an in-cabin thermistor. These systems are reflected in factory diagnostics and OBD-II fault codes such as P0115–P0119 (ECT), P0110 (IAT), and P0711 (ATF temp), as documented by Toyota service information and standard OBD references.

On a 2007 Highlander, temperature sensors quietly keep everything behaving. The ECT sensor tells the engine computer how hot the coolant is, so it can sort cold starts, fuel trim, ignition timing, and when to switch the fans on. The IAT sensor helps fine-tune fuelling based on the temperature of the air heading into the intake. Out on the road, the ambient sensor feeds the outside temp display and guides the HVAC, while the evaporator sensor prevents the A/C core icing up. The transmission temp sensor looks after shift quality and gearbox protection by reporting ATF temperature.

There’s no set service interval just for temperature sensors, but they’re worth a check when doing routine maintenance. A proper scan with live data is the go-to: on a cold engine after an overnight park, the ECT, IAT, and ambient readings should be close to each other and close to the local air temperature. If one is way off, that’s a clue. Inspect connectors for corrosion or broken tabs, and chase coolant leaks that can wick into the ECT plug. When replacing the ECT sensor, work on a cool engine, catch and top up Toyota Super Long Life Coolant (pink) as needed, fit a new sealing washer if specified, and tighten to the factory spec in the service manual.

For the IAT in the MAF body, never scrub the sensing element—use only MAF-safe cleaner and let it air-dry. If the ambient sensor at the front of the car reads oddly after a minor bump, check the bracket and wiring. Transmission temp faults (e.g., P0711) often call for proper ATF level checks and, if needed, internal sensor diagnosis as outlined in Toyota’s repair procedures.

• Common signs of a crook temp sensor: hard cold starts, high idle that won’t settle, rich running or poor economy, cooling fans stuck on or never coming on, erratic A/C, or a Check Engine Light with codes like P0115, P0117, P0118, P0110, or P0711.
• Best practice: verify with scan data, confirm wiring integrity, and use quality OEM-spec parts for replacements.

Look after these little sensors and the Highlander will repay the favour with smoother starts, steadier temps, and fewer headaches on long kilometres around Australia and New Zealand.

FAQs

Where is the engine coolant temperature sensor on a 2007 Toyota Highlander?

On both the 2AZ‑FE 2.4L and 3MZ‑FE 3.3L engines, the ECT sensor threads into the water outlet/thermostat housing near the front of the engine. It’s typically below or beside the upper radiator hose connection. Access is straightforward with basic hand tools once the engine cover is off.

What are the symptoms of a bad temperature sensor on a 2007 Highlander?

Expect hard or rich cold starts, high idle, poor fuel economy, cooling fans running constantly, a dead outside-temp reading, or erratic A/C cycling. The Check Engine Light may set codes like P0115–P0118 (ECT) or P0110 (IAT). Live scan data that doesn’t match actual ambient temperature is another giveaway.

Can you drive with a faulty coolant temperature sensor?

It may still run, but it’s not ideal. The ECU can go into a default strategy that overfuels, risks catalyst damage, and may trigger cooling fans at odd times. For reliability and to avoid bigger repair bills, it’s best to diagnose and replace the sensor or repair the wiring promptly.