BMW E-series 2009 CAS module corrupted

Here is what happened

The case of a CAS module corrupted of BMW E series 2009 where the keys were lost

Having the right equipment for the job is very important. In this case, this was the issue. The customer has brought the car to us because the previous auto locksmith company was not able to properly program new keys since the ISN was not correctly extracted due to lack of equipment or expertise. When they attempted to obtain the ISN, the CAS module was corrupted. On these models, the CAS module can be recovered, but some need to be replaced. The rate of recovery of corrupted CAS modules is high.


In a recent study, RAC has found that almost 2 million drivers admit having lost their car keys for good. 6% of them acknowledged losing their keys a second time. When further questioned about where they might have lost them, a whopping 23% of them responded that they have no idea, while 18% of them thought that they lost their keys when out of the house, 9% misplaced them somewhere in the house, 5% said they lost the keys at work and about the same said that they lost their keys while shopping.

Who to call when losing or misplacing the car keys

Today, doing a million things at any one point in time can cause the brain sometimes not to process the essential task such as remembering certain events. If such an event involves not remembering when or where you saw your car keys last, then you should ask yourself who do I call? The best answer is an auto locksmith company that is well established, equipped with the sophisticated and up to date main dealer level, equipment and has trained technicians to properly deal with any situation they might find themselves in. It is essential to remember when choosing an auto locksmith company, that the cars are not what they used to be and that they require a great deal of expertise, experience and proper equipment to deal with the issue at hand without causing further damage.



What is ISN?

ISN is not a software, but it is rather an immobiliser key code that is held into the CAS module, and it is also written on the car key. If the ISN code is correctly written on the car key, the CAS module will recognize it when inserted in the ignition switch and then it will enable the starter.

What CAS stands for and does this module do?

CAS, also called car access system, is the main unit controlling the immobiliser system of a BMW and it has integrated the car key security software data.
To enable the engine to start, first, the CAS unit must recognize a matched key in order to allow the ignition to come on and release the electronic steering lock. Once the ignition is switched on then the ISN code on CAS unit, DDE/ DME(engine control unit) and EGS(transmission control unit) are compared.
If the code matches the engine starting is authorized, and transmission is ready to operate. If the CAS unit detects a different ISN code from the DDE/DME engine starting will be prohibited. On some late BMW’s EGS also has immobiliser functions integrated, meaning there is an ISN programmed on it. If this code is not matched with the CAS unit the selector lever won’t operate, basically the transmission function will be stopped.

BMW the pioneer of the integrated immobiliser

Since 1994, BMW added a new technology to protect the vehicles against theft. This new technology was a device, called EWS and is the pioneer of the integrated immobiliser function. From 2003 onwards, the immobiliser function initially integrated into the EWS module was changed to be controlled by the CAS module.

Both CAS and EWS modules compare the VIN number between various modules in the car. If the VIN numbers programmed don’t match, the vehicle will not start.

We have just recently received in our workshop a BMW 325i from 2009 with no keys after a failed attempt to program a new key.
Once the car was in our shop, we first attempted to connect with the car, but there was no communication. CAS unit was partially responding and incorrect data, chassis number was altered. This was an indication that software was corrupted internally. We managed to recover the CAS module by rewriting the software and successfully adapting the CAS to the car. After we had extracted the ISN code, we proceeded with the programming of two new car keys and got the BMW up and running yet again.


Always use an experienced auto locksmith company.

As we mentioned earlier, today’s cars are not what they used to be. For just cutting a car key and programming a new car key, if not done with the proper equipment and by a qualified auto locksmith, one can end up spending a few more hundreds of pounds in addition to what would typically be the cutting and programming of the new car key. In addition to this, the inconvenience of not having the car available for use. This was the case of our customer, which is now happy to have his Bimmer back on the road, and for the fact, we saved him the cost of a replacement CAS unit but wasn’t a few days ago.

When you need a BMW auto locksmith make sure you use a trusted one.

You may be interested to read about Car key and lock protection tips or about Auto locksmith the beacon of hope for locked-out car owners.