Fortuner Engine Overheating

I had a similar issue with my older Fortuner. Your symptoms sound familiar. It turned out to be a defective map thermostat. Have you checked the thermostat housing for coolant leaks? How's the temperature sensor behaving? Is it giving consistent readings, or is it fluctuating wildly?

I haven't checked the thermostat housing for coolant leaks, but I will. I haven't monitored the temperature sensor closely. Where is the sensor located, and what are normal vs. abnormal readings? Is it a difficult and expensive repair? Should I do it myself?

The sensor is usually near the thermostat housing. Consult the service manual for exact specifications on normal readings, but erratic fluctuation is a red flag. A defective map thermostat is often the culprit. If you aren't comfortable with car maintenance, seek a professional mechanic's help, as diagnosis can be tricky. I had mine swapped out at a workshop.

A defective thermostat seems likely. I'll schedule an appointment with a trusted workshop to inspect the thermostat and temperature sensor. I will post the solution. It cost me around 350€.