What Causes the BMW Trunk to Open Automatically?

[VanNora]

The automatic opening of a BMW's trunk may occur if the car door is not properly closed. Another possible scenario is when the BMW detects the presence of the key inside the car, which prevents the trunk from closing. Trunk automatically opens when a key is detected inside: When the BMW detects the key inside the car that was used to lock the doors, the trunk cannot be closed. The trunk door consists of upper and lower sections, and sometimes if the lower section is not properly closed, it may also open automatically. The trunk lid can be opened via the interior operation button, the external trunk button, or the remote control. It can be closed using the external trunk button, internal button, or remote control. How the trunk works: The trunk lid module is connected to the internal trunk button. The trunk lid interlock is controlled by the power module (PM), with information received and transmitted via the K-CAN data bus. The external trunk button is directly read by the power module and forwarded to the trunk lid module. The interior trunk button is read by the comfort access and start system and transmitted to the trunk lid module. When opening the trunk, the trunk lid lock is first disengaged by the unlocking mechanism. If the power module detects that the lock is open (via the trunk lid contact grounding), the automatic closing mechanism is activated.

[SebastianLynn]

Last month, my BMW had this issue where the trunk kept opening automatically. After checking, several common causes were identified. A weak remote key battery can mistakenly trigger the button, or the key might get pressed in the pocket, sending random signals. Another reason could be water damage or a faulty trunk lock sensor, especially prone to failure in rainy or humid conditions. Occasionally, the electronic system might short-circuit or experience software glitches, particularly in newer models with smart opening features, which are more vulnerable. To prevent issues, I make sure not to leave valuables in the trunk. For a temporary fix, you can remove the remote battery or manually lock the trunk. Stay calm and drive safely. If you're really concerned, take it to a shop to check the wiring or replace fuses. Don't delay, as it could attract thieves or pose safety risks. The repair cost is usually around a few hundred dollars.

[WalterLynn]

Having driven a BMW for over a decade, the trunk opening by itself is mostly a hardware issue. Common causes include wear and looseness of the tailgate latch preventing it from securing properly, or mud covering the sensor probe reducing its sensitivity. Electrical issues like blown fuses or cracked wire insulation causing short circuits are also possible, especially in older cars with high mileage and aging parts. Sticky remote control buttons causing accidental presses can be annoying—try replacing the batteries first. Temperature changes can easily cause electronic components to fail due to thermal shock, so extra caution is needed on rainy days. If you notice a malfunction, never ignore it before driving on the highway—sudden opening is very dangerous. Contacting the brand's after-sales service for timely inspection and repair is always the right move, as they have complete tools for quick diagnostics.

[DiElla]

The trunk opening unexpectedly is quite frightening. If valuable items fall out or it's windy and rainy, it could be disastrous. Possible reasons include insufficient battery in the remote control sending false signals, or accidentally pressing buttons when squeezed in a bag. The lock might be jammed by foreign objects preventing it from closing properly, or a mischievous child might have pressed the switch. The electronic control module could occasionally freeze and fail to respond, especially in models with hands-free opening features. It's advisable to check if the trunk is securely closed when parking and to do a quick inspection around the car before starting to avoid losses. Timely software updates to fix bugs are crucial. Pay attention to anti-theft security at night or in unfamiliar places, and developing good habits can prevent major issues.