Trafic door lock issue

I had a similar problem with my Renault Trafic. It sounds like the cable or plug connection might be defective. The door sensor sends signals to the car's computer, and if the connection is bad, the door won't lock/unlock. Have you checked the wiring around the door frame?

Thanks for the tip! Where exactly should I be looking for the cable and plug connection? Is it something easily visible, or do I need to remove any panels to access it? By wiring around the door frame do you mean the car's side, or inside the door?

It's often inside the door, near the latch mechanism. You might need to remove the door panel to get a good look. To be honest, it's a bit fiddly, and if you're not comfortable with car electrics, a workshop might be a better bet. If its similar to my issue, the repair cost should be around 95€

Thanks a lot for your help! I took it to a local workshop, and it turned out to be exactly what you said – a defective cable connection. They fixed it for 95€. Appreciate the advice!