Peugeot 107 Alarm System Fault

Sounds like a bit of a pickle! Has anything else been happening, like battery issues or aftermarket installs? Sometimes a low battery can cause systems to act strangely. Did this start suddenly, or has it been gradual?

The battery seems fine, and there are no aftermarket installs. The failure was pretty abrupt. When you say 'poltergeist', do you mean an intermittent electrical fault, or something software-related?

The poltergeist was mostly an analogy. Abrupt failures often point to something specific gone wrong. It's probably best to have a workshop take a look and properly diagnose the coding. The optical locking might be a red herring; a proper diagnostic should reveal the root cause.

I appreciate your input; it reinforced my decision to visit a workshop. The issue was as suspected: the alarm system was coded to activate optical locking. Reprogramming the alarm system fixed it, costing 45€. The car now works as it should. Thanks again for your guidance.