What Causes a BMW Horn to Stop Working?
2 Answers
The following are specific reasons why a BMW horn may stop working: 1. Water ingress due to poor sealing: The horn is internally sealed, but if the seal is not tight, water vapor can enter during car washing, causing the contacts to become damp and malfunction. 2. Poor contact at the electromagnetic coil terminal: The terminal connections of the enameled wire in the horn's electromagnetic coil are made of aluminum. If the insulating paint on the wire ends is not properly removed or the rivet connections are loose, poor contact can occur, leading to horn failure. 3. Contact erosion from prolonged use: Extended use of the horn can cause the contacts to erode, creating resistance. This reduces the current through the electromagnetic coil, preventing it from attracting the armature to vibrate the diaphragm properly, resulting in a non-functional horn. However, when the horn is pressed repeatedly, the momentary high current can still pass through the resistance, causing intermittent functionality.
I've been in the auto repair industry for many years and often deal with BMW issues like this. There are quite a few reasons why the horn might not work: the most likely culprit is a blown fuse. You can find the corresponding horn fuse in the cabin fuse box and try replacing it. If changing the fuse doesn't help, it could be a wiring issue, such as a loose connector or aging wires, especially in the front of the car where impacts can cause deformation. The button switch on the steering wheel is another common failure point—over time, the contacts wear out, preventing signal transmission. In some cases, the horn itself might be faulty, and humid weather can make short circuits more likely. Insufficient battery voltage can also affect current supply. I recommend starting with the fuse check first. If you can't pinpoint the cause, it's best to have a professional shop inspect the circuit, as a non-functioning horn can seriously compromise safety on the road.
