BMW Hood Open Warning | Bonnet Switch Sensor

Does your hood open warning light appear on your BMW dashboard even though the hood is closed? Learn how to fix it by following the procedures below.

Problem

A common problem with the BMW hood sensor is that you get a hood open message on the dashboard even when the hood is closed, or the car alarm goes off randomly without anyone touching the car. This problem is often solved by replacing the BMW hood switch.

Symptoms

A bad hood latch switch can cause a warning message on the dashboard / iDrive or trigger false alarms. The sensor may fail on its own.

• Hood warning message on the dashboard
• The car alarm goes off randomly when the car is locked.
• False bonnet open warnings on iDrive

The most common signs of a bad BMW hood switch are hood open (bonnet open) warning and false alarms.

Often, a BMW owner may notice these symptoms after a car wash.

Procedure

To permanently fix this problem, you must replace your BMW hood switch. The procedure is very simple and takes about fifteen minutes.

1. Park the BMW, set the parking brakes, and turn off the engine.
2. Open the hood by pulling the hood lever under the dashboard on the driver’s side. Pull or press the hood release at the front of the hood and lift the hood.
3. Locate the hood switch towards the back of the engine. The hood switch is on top of the plastic over the firewall.
4. Press the connector and unplug the wire harness from the sensor.
5. Remove the sensor from the bracket using a flathead screwdriver. On some models, you may need to remove the cabin air filter housing to remove the hood switch.
6. Install the new sensor by pressing it in the bracket.
7. Connect the wire harness to the hood switch.

Temporary Fix

There are a few temporary solutions that you may want to consider until you get a BMW hood switch replaced. Note that these solutions are not recommended for the long term.

The recommended fix is to replace the BMW hood sensor with the new one. The sensor is inexpensive and ranges in price from $10-$30.

• Disable Hood Switch: When you lock the car using your key fob, press the BMW logo on your key twice. This will disable the input to the alarm system from sensors such as the hood switch. Note that doing so may make it easier to break into your BMW.
• Disconnect Hood Switch: Unplugging the hood sensor is another temporary solution. You are disabling input to and from the sensor by unplugging the wire.
• Repair BMW Hood Switch: Remove the switch and open the housing. Clean the contacts inside and manually stretch (lengthen) the spring inside the sensor. This will usually fix a BMW hood open problem, but the problem may return within a few weeks or months.

Frequently Asked Questions

We hope you find the BMW Hood Open Warning | Bonnet Switch Sensor guide helpful. Check these troubleshooting and repair guides for more help on your BMW.