Trunk lid won’t open and rubber button (Citroën C4)

Unlike other cars, the C4’s button is not mechanical, but rather a… electrical microswitch Protected by a rubber cover. Over time, this rubber dries out and tears, allowing moisture to enter, or the internal plastic support breaks.

• The Real Problem: 1. Infiltration: Water enters through the torn button and oxidizes the microswitch contacts. It stops sending the signal to the BSI to release the latch. 2. Broken wiring: In the C4 Hatch, it’s very common for the wires that run through the “accordion harness” (between the trunk lid and the body) to break from opening and closing the trunk so often.
• How to Open in an Emergency: If the button fails, you can open the trunk from the inside. Fold down the rear seat, enter the trunk with a small screwdriver, and insert it into a small hole in the interior lock. Push it to the side, and the trunk lid will unlock automatically.

Location of Protection (Fuses): If you press the button (or use the remote control) and don’t hear any motor noise attempting to start, check the BSI (inside the cabin):

• Correct Fuse: It’s the fuse. F7 (20A) or F14 (15A)Depending on the year/model, it protects the power locks and the trunk release.

Maintenance Tip: If the button is “loose,” you don’t need to replace the entire lock. You can buy just the external switch (the opening “handle”) on auto parts websites, and replacing it simply involves removing the interior trim of the cover.