Vauxhall Vectra remote locking bumper antenna issue

I had a similar issue with my Vectra. The symptoms you described are nearly identical to what I experienced. Have you checked the FM antenna connection? Sometimes, corrosion or a loose connection there can cause signal interference which might affect the central locking system.

When you say check the FM antenna connection, are you referring to the base of the antenna, or is there another connection point I should be looking at?

Yes, I meant the base of the antenna. I'd recommend checking both the connection at the antenna base and the connection to the radio unit itself, if accessible. However, given the starting issue, it might be best to let a workshop diagnose it. They have better tools to pinpoint electrical faults.

Understood, I appreciate the advice. I will check the connections, but I will likely take it to a workshop given the potential complexity. They quoted me around 95€ for the job.