What Causes a BMW Horn to Stop Working?
3 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.
I've been driving my BMW for several years, and last year the horn suddenly stopped working. At first, I thought it was a button malfunction. I checked it myself: I opened the hood to see if the horn wiring was loose, but found nothing wrong; then I went to the fuse box, replaced the fuse corresponding to the horn, and it was fixed. Later, a friend told me that this issue is common in older car models, possibly due to poor wiring contact or corrosion of the horn components. If you're not careful when washing the car, water can seep into the engine area and cause problems. For prevention, it's recommended to regularly clean the connection points to prevent dust buildup. If you're not confident in your DIY skills, you can also take the car directly to a 4S shop to test the switch module, saving yourself the hassle. In short, don't ignore small issues to avoid the frustration of the horn not working when you need it most.
