Fortuner solar sensor fault

Interesting. I recall facing a similar problem with a daylight sensor in my previous Volvo V70. Different sensor, different brand, but the symptoms you describe sound familiar. Just to clarify, have you checked the sensor calibration? Is the error intermittent, or is it constantly present?

Sensor calibration? I haven't checked that, no. Where would I even begin to check the calibration on the solar sensor? Also, the error is constantly present, it doesn't seem to come and go.

Alright, since the fault is constant, calibration may not be the immediate issue. In my case with the Volvo, the faulty sensor was indeed the root cause. It seems like you have checked the obvious things already. I suggest getting the sensor checked out professionally, because the HVAC system in these vehicles can be quite complex. You might need special diagnostic tools to pinpoint the exact cause. I would advise that you take the car to the workshop.

Thanks for the insight! I appreciate the advice. Booked it in with a mechanic, turned out to be a defective cable. Repair cost about 95€. Thanks again!