Fortuner low heating output

That's odd. I had a somewhat similar heating problem with my old BMW 3 Series, although not exactly the same. The heat was intermittent, and it turned out to be a faulty thermostat. Did you check the coolant level? Also, what error code are you getting? Knowing the error code could really point you in the right direction.

Thanks for the input! I did check the coolant level, and it seems fine. I'm not sure about the exact error code at the moment, I'll have to check again. Is it possible it's really just a faulty thermostat in my case as well? What was the clue that made you think it was the thermostat in your BMW?

Well, the error code on my BMW specifically pointed to the thermostat being the issue. Plus, the temperature gauge was fluctuating wildly. If your coolant level is okay and you're not seeing any temperature fluctuations, it might not be the thermostat. But without the error code, it's hard to say for sure. I'd recommend getting the error code read properly and then taking it to a workshop. It could also be a blockage in the heater core or an issue with the blend door actuator.

Alright, thanks a lot for the advice! I finally got the error code read. You were right, it wasn't the thermostat. Turns out it was indeed the water valve, like I initially suspected. The cable connection was defective, just as I guessed. The repair cost me around 95€. Appreciate your help!