When you have issues with your BMW airbag the airbag light will turn on from your dashboard. This could be a problem with your Supplemental restraint system (SRS) and this can pose serious problems when involved in an accident as the airbags can refuse to deploy effectively. It is almost impossible to rest the airbag light without the need for the BMW scanner.
Signs you have issues with your airbag
One of the first symptoms that you have issues with your airbag is that the BMW airbag light is illuminated on the dashboard.
You may also start receiving the pass restraint system message, here you will get a message that goes something like “ Fault in passenger restraint system affecting airbag, belt force limiter or belt tensioner. Continue wearing a seat belt”
How to diagnose faulty airbag
- You will need a BMW scanner for this. These will allow you to read and clear codes from the airbag control unit.
- The first step is to locate the OBD-2 port. You will find this under you dash for most modern BMW models. Connect your scanner to this port.
- Turn on the car ignition without starting the engine
- Once the scanner has turned on go to the BMW chassis and model and select it
- To navigate to the SRS control unit, select BMW then control units followed by body safety. Once you reach the SRS control unit you should be able to read airbag fault codes
- Next clear the airbag control unit codes by scrolling through the menu to clear fault codes
You should note that the airbag codes can only be reset if the said code is in stored the SRS units memory. Also, note that if the problem that caused the light is not solved the codes will come again.
At times disconnecting your battery will reset the airbag light.
When you are handling airbags always ensure you are two feet away from it.
What are some common issues that trigger the airbag light
One of the most common reasons for a fault airbag light is the passenger occupy sensor. This sensor is also known as the seat sensor pad, child sensor, occupancy sensor or passenger mat. The sensor is put in place so that it can monitor whether a person is of a certain weight. In this case if the person is not over a certain weight like in the case of a child the airbag will not deploy hence harming the occupant. When this sensor fails it may cause the airbag light to come on.
For BMW with iDrive when their problems with the passenger airbag you will get a message on the screen. This problem can only be fixed by replacing the seat sensor. You can do this yourself by removing the seat and cushion or go to a dealer who do the replacement for around $500. The passenger seat sensor normally goes for around $200 and above.
Low battery voltage
The BMW airbag light can come on and remain on if you have recently replaced a dead battery or have jump started your car. In this instance, your SRS control unit will record a under voltage fault code. If you disconnect the battery while the key is in ignition you may also get this error code.
You clear this error code via your BMW scanner tool.
Seat belt buckle
Another reason for airbag light turning on is the seat belt buckle switch. This small switch sends signals to your car that you are in your seat. When it is defective the car could be detecting it but the airbag control unit maybe missing it hence the light coming on. You can solve this by pressing the seat belt buckle several times and see whether the airbag light will come off. If it doesn’t you may want to have it checked with an auto mechanic.
Seat belt tensioner
The pre-tensioner is used to tighten your seat belt safely whenever you encounter an accident. If there are issues with the seat belt tensioner then the light will turn on. When you use your BMW scanner to diagnose the error codes you will experience one that points to the pre-tensioner.
Defective clock spring
To diagnose this you notice that your horn is not working well but the airbag light remains on. The reason for this could be your clock spring. You can replace this by locating it behind the steering column behind the steering wheel. In some BWM models like the E36 it is integrated with the steering wheel which means if it is bad you will need a new steering wheel. For most cars you can remove the steering wheel then replace the clock spring.
If your BMW has being involved in an accident then your airbag light might come on. This takes place even though you have replaced the previous airbag. The reason for this is because the crash data is stored in your SRS control unit and it is hard to clear it with a scanner. You have two options when this happens. The first option is to take your BMW to a dealer who will erase all data from the SRS control unit and the second option is to replace the entire airbag control unit. The later can be quite expensive.
Disconnected airbag sensor
The airbag light can also be activated if you accidentally unplug the airbag sensor as you are working on the car while the ignition is on. To prevent this from happening you should disconnect your battery whenever you are changing a window or bumper. To resolve this reconnect your sensor then use scanner to clear the codes. The same will apply if there are any loose wires that lead to the sensor.
There are a number of reasons for the airbag light to go on and it is, therefore, prudent to use a BMW scanner to clear the error codes. Before clearing the codes you should diagnose the cause for the light coming on otherwise it won’t go off even when you clear the codes.