Peugeot 108 Starting Issues

The symptoms you describe – engine failing to start, unexpected shutdowns, and rough running – do point towards a potential ignition system fault. Whilst fuse integrity is paramount, the issue is unlikely to be fuse-related given the multifaceted nature of the problem. A defective ignition switch can indeed cause these problems. The intermittent nature further supports this assessment. Have you observed any correlation between the key turn position and the occurrence of these issues? Does the starter motor engage consistently when you turn the key?

I have not noticed a specific key position that causes the issue more frequently. It seems to be random. The starter motor does not always engage when I turn the key. Sometimes there is nothing at all, and other times it cranks but the engine doesn't fire. Could this still be the ignition switch or potentially the starter motor itself?

The fact that the starter motor sometimes fails to engage strengthens the suspicion that the ignition switch is the root cause. A failing switch can disrupt power delivery to both the starter solenoid and the engine management system, explaining the range of symptoms. Whilst the starter motor itself could also be failing, that is less likely given the other symptoms. I would advise a professional assessment, as diagnosing ignition switch faults can be complex, requiring specialized equipment. You should expect to pay around 52€ for the repair including parts and labor.

I took it to a local workshop, and it turned out that the ignition switch was indeed faulty. They replaced it, and the car is now starting and running perfectly. I appreciate the confirmation and advice!