Peugeot Expert Automatic Temperature Control Issue

Sounds like a sensor issue. Is it showing any specific fault codes? Have you checked the basic stuff like fuses related to the climate control? It could be a faulty interior temperature sensor – those can cause all sorts of havoc with the system.

I haven't pulled any specific fault codes myself, just a generic error message related to the HVAC system. Where exactly is the interior temperature sensor located? I'd like to check it and the connections before going to a workshop.

A generic HVAC error does point to a sensor issue. The interior temperature sensor is usually located somewhere on the dashboard, often near the steering column or in the center console. Check the cable and plug connections. A defective cable or connection is the most likely cause. If you can't find anything, or the sensor looks damaged, it's best to get it checked professionally.

Your sensor and connection diagnosis was spot on. The shop confirmed it was a bad cable to the interior temperature sensor. It cost 95€, and now it's fixed.