BMW Passenger Restraint System Malfunction: Reasons & Fixes

The passenger restraint system in your BMW combines airbags and seat belts with associated sensors and wirings. The purpose of this system is to deploy protective measures in the unfortunate event of an accident. So, a BMW passenger restraint system malfunction demands your immediate attention to ensure road safety.

One main reason for this malfunction is a defect in the airbag wiring or the SRS module. Water damage or a worn-out passenger seat sensor can also damage the sensor. Depending on the cause, you might resolve the problem by identifying and replacing the faulty parts.

Seeing the passenger-restraint-system malfunction notification is annoying and a cause for concern too. However, with proper knowledge, you may be able to fix the issue yourself and not have to call an expert.

Signs of a Failing BMW Restraint System

There are mainly two signs that tell you your BMW restraint system is failing. If you encounter any of these, you must take proper steps to resolve the problem.

Dashboard Message

The passenger-restraint-system malfunction message displays on the dashboard as soon as you start the car. The wording and sentences might vary according to the model of your BMW.

Usually, it says your passenger restraint system is malfunctioning and affecting the airbags, belt tensioner, and belt force limiter. 

Plus, the message also advises you to keep wearing the safety belt. It might also suggest you take the car to the nearest servicing station as soon as possible. This is the surest sign you are experiencing a malfunction.

Lit Airbag Sign

The Airbag light staying on is another indicator of a malfunctioning restraint system. Usually, the light comes on when a person occupies the passenger seat of your car.

The lit airbag sign is a cause of great concern. Because it indicates that the airbags have become unresponsive; in other words, they wouldn’t explode out and save the respective passenger in the event of a crash.

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What Can Trigger A BMW Passenger Restraint System Malfunction?  

There are many reasons why your BMW passenger restraint system might malfunction. The main reason is often a fault in the airbag’s sensor and wiring. But low voltage or water leaks might also be the issue.

1. Airbag Problems

Your BMW has front airbags in the steering wheel area and inside the dashboard of the passenger side. Depending on the model, there might also be side and curtain airbags. These bags activate during an accident and minimizes the degree of passengers’ chest and head injury.

A wire harness connects your airbags to the car’s internal operating system. This harness might damage over time and weaken the connection between your car’s restraint system and the airbags. As a result, the system detects unresponsive airbags, lights the signs, and shows the message.

Also, if your BMW has previously been in an accident or frontal impact, the airbags may not have recovered properly. This will also trigger a restraint malfunction.

2. Issues With SRS

The supplemental restraint system controls the airbags. It has impact sensors that can detect collisions and send a signal to inflate the bags with nitrogen gas.

Now, the impacts would be sufficient to alert the sensors if your driving is rough. However, it will not be significant enough to inflate the bags. In that case, your dashboard will show the passenger restraint malfunction message.

On other occasions, the reason might simply be a bad sensor. The impact system loses its ability to process data properly as time passes. As a result, the restraint system will malfunction.

3. Damaged Occupancy Sensor

The passenger restraint system has many sensors across your car. The occupancy sensor is one of the most important ones. It is installed under the passenger and driver seats. The sensors detect whether a passenger is occupying a seat and deploys the respective airbag in the event of a crash.

As these sensors constantly bear weight, they encounter a lot of stress which damages them over time. When that happens, the passenger restraint system can’t know if it activates the airbags in front of that seat. As a result, a malfunction occurs.

4. Not Getting Enough Power 

The passenger restraint system needs adequate electricity to keep itself running. So, if your car battery cannot provide the required electricity, a BMW restraint system will malfunction.

There are multiple reasons why your battery can’t convey power. Firstly, the wire connections might have become loose or corroded. Another reason might be that the passenger restraint system fuse might have blown out.

Also, BMWs deploy a system in their cars known as Battery Safety Terminal. The system prevents the incidence of electrical power in the event of an accident. If the BTS cable is damaged or corroded, the restraint system will fail. Additionally, you will experience overall low power. 

5. Defective Seat Belt Tensioner

The seat belt is a vital element in the BMW passenger restraint system. It prevents any uncontrolled and excessive movement of the passenger during an accident. Plus, it compliments the airbag system by holding the passenger in the correct position.

To make this possible, the seal belts have pretensioners. During normal driving, the seat belt is slightly relaxed to prevent any discomfort to the passenger. But whenever your car comes to an abrupt stop, the pre-tensioners detect it as a possibility for collision and tighten the belt to secure the passenger’s position.

When these pre-tensioners stop working properly, your restraint system malfunctions. As a result, you might see the message appear on the dashboard.

How to Fix the Restraint System Malfunction BMW?

Your passenger restraint system is a highly important part of your BMW. Getting a warning message on the dashboard is a cause of great concern. 

Because driving with a failing restraint system puts you and the other passengers at risk of fatality. You can perform the following to fix the restraint system-

  • Check for burnt-out passenger restraint system fuse.
  • Inspect the vehicle for any internal water leakage.
  • Repair the Airbag wiring harness.
  • Get New SRS sensors.
  • Install new passenger occupancy sensors.
  • Correct the battery connections.
  • If necessary, replace or repair the BTS system.
  • New pre-tensioners for your seat belts.

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Hopefully, the above discussion was adequate to satisfy your queries regarding the BMW passenger restraint system malfunction. However, we might have missed some things. So, feel free to ask us more on this topic. 

Can I drive my BMW with a passenger restraint system malfunction? 

Yes, you can drive with a malfunctioning passenger restraint system. Although, you might want to ask yourself whether you should. Because in the unfortunate event of a collision, your chance of fatality would be very high. 

How much do I spend on replacing the airbag sensors of BMW? 

The airbag crash sensors or impact sensors replacement is somewhat costly. On average, the sensors are priced at around 200-300$. And unless you are an automobile expert, you must hire a professional to install these sensors. That can cost you another 200$. In total, you might have to spend 500$.

Is replacing the BMW passenger occupancy sensors costly? 

The passenger occupancy sensor replacement is cheaper than the crash or impact sensors. The parts will cost you around 100$. Meanwhile, the labor cost can be in the range of 100-150$. So, you can hope to complete the job within 200$ or a little more. 

Where can I find the BMW passenger restraint system fuse, and what’s the cost of replacing it? 

First, open the trunk of your BMW. Under the hood, you will find a map of all the fuses in your car. From there, locate the one associated with Airbags and note the serial number. Afterward, go to the glove box, find the fuse with that number, and pull it out. A new fuse can cost you 10$ or less. 

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Final Thoughts

The bmw passenger restraint system malfunction is a life-threatening issue. What’s more dangerous is that you might ignore it because it doesn’t stop you from driving the car. However, you will wish you had taken it if you have ever had the misfortune of being in a car accident. 

Remember, it’s not only your life that you are putting in danger but your family members too. Always conduct an inspection based on what you learned here before taking the car to a professional. 

That way, you might be able to save a couple of hundred dollars. On the other hand, leave the installation of impact sensors to the professional, even if it takes a few bucks out of your wallet. Because proper installation can make the difference between life and death here.

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