3 Possible Symptoms To Detect BMW CAS Module Failure With Tips

As we all know electronic devices eventually start to malfunction as time goes by. BMW has a system that is quite dependable, yet the CAS system can still malfunction. Finding and comprehending the symptoms will make it simple for you to solve the issue. Thus, you should know about the BMW CAS Module Failure Symptoms 

The common symptoms of CAS module failure include faulty messages on the iDrive screen, your BMW not starting, Key detection issues, and many more. However, do keep in mind that fixing defective CAS modules is a bit complex hence understanding the symptoms is essential.

Thus if you are wondering if your BMW CAS module has failed and looking for the symptoms, our guide will help you find that out. 

What is CAS Module In BMW?

The Car Access System is referred to as CAS. The CAS performs a number of different functions. However, the two primary tasks are starting the car and keeping an eye on the anti-theft burglar alarm. The CAS system often sits under the steering column. 

For safety reasons, the CAS module creates a random key code for each time your BMW is turned on and synchronizes it with the ECU. 

Prior to sending an enable command to the starter, it verifies the crucial data to make sure it is accurate. Therefore, to start the car, CAS must couple with your key.

Read Also: 6 Common BMW Fuel Pump Control Module Failure Symptoms

What are the common BMW CAS module failure symptoms? 

There are many different symptoms that can happen when your BMW CAS module fails. These symptoms will help you detect the issue even more quickly. 

When the CAS module fails on a BMW, you will need to reprogram the whole thing or replace it. Keep on reading to know more. 

#1- Faulty messages on the iDrive screen

The first and most common symptom of a faulty CAS module in your module is a malfunctioning message on the iDrive screen. 

The iDrive screen on the BMW is like a computer control system of your car, and this will show you all the information related to your engine and other parts.

So, when the module fails, you will see a CAS malfunctioning message on the screen, and this means you should check the system before going on a drive. 

This problem can get solved sometime simply by reprogramming the module instead of replacement. 

#2- Car not starting 

Another common symptom that you will notice when the CAS module fails is that your BMW will not start. 

The car will remain steady as a consequence, and the engine won’t start or function. Additionally, you might see symptoms like the engine will turn over, but it won’t be able to start. 

This usually happens when the CAS system gets wholly damaged due to water or a short circuit inside the circuit wirings. If this happens, you will need to replace the CAS module. 

#3- Key Detection issues

When the CAS module in a BMW is faulty, the key cannot be correctly detected. Code saved in the DME/DDE module and code in the CAS module might be out of synchronization. 

As a result, the code won’t get matched whenever you put in the key, and your car engine won’t get started.

So, use the DDE/DME module’s CAS resetting operation to fix the problem. Resetting the CAS is a reasonably easy procedure, and you can easily do it yourself without consulting any mechanic for it.

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Tips to Consider when the CAS Module fails 

When the CAS module on your BMW fails, follow these tips below to make sure that the new module works perfectly and doesn’t cause any more damage in the future.

  • If the CAS module fails, sometimes resetting the module will fix it up, and you can do it yourself.
  • Replacing the module is a bit complicated, so you should consult a professional mechanic for the work.
  • Always keep your CAS module protected from water, as water can damage the whole system. 
  • When buying a new CAS module, make sure that the module is of the same model as your previous one. 

Read Also: What Causes BMW Drivetrain Malfunctioning & Car Won’t Start?


Down below, we will discuss all the faqs that might have popped into your head after reading our guide so far. 

What Is The Replacement Cost Of The CAS Module In BMW?

Costs for an OEM BMW CAS range from $1000 to $2000. Your current CAS will require a CAS troubleshooting test to determine if it can be repaired or whether a replacement is necessary. However, you can also find less expensive reconditioned CAS modules. 

Where Is The CAS Module Located In BMW?

Under the steering column is where you’ll find the BMW CAS module. You should crawl below the dash on the driver’s side. Then you must take off the plastic cover beneath the dash just above the brake and gas pedals in order to reach the CAS module.

How Does The CAS Control Module Enable Engine Start?

The DME/DDE receives an encoded activate signal from the CAS control module through the data connection. This signal must be transmitted before the engine may be started. Only when a valid enable signal is received by the engine control module (DME/DDE) does it allow the engine to start.


The CAS module is one of the most important components of your BMW. When this gets damaged, your car won’t be able to start. Moreover, it will also show problems with key detection.

You might think of replacing the whole CAS module, but that can be expensive. Luckily, sometimes resetting the module can bring the CAs back to perfect working conditions, and you can reset the module by yourself.

However, if you have no option left but to replace the whole module, it is better to get help from a professional mechanism for the replacement. 

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