Toggle menuThe ECU Pro
Tue Feb 27 2024

BMW CAS Module Repairs: Common Fault Codes and How to Repair Them

What Is the BMW CAS Module? 

First introduced in the E65, the BMW's CAS Module is located directly under the steering column and serves three important purposes.

First, it makes it possible for your vehicle to start. Second, it monitors your car's anti-theft alarm system around the clock. Third, it stores your vehicle order (VO). 

Your VO is the coding that knows, remembers, and controls all of the features in your car. It has information on a range of different features and functions, including: 

  • Transmission type
  • Engine type 
  • Vehicle identification number (VIN)
  • Special or extra features

While some of these functions might seem more important than the next, it's crucial to keep safety and security top of mind, especially when you're behind the wheel of a luxury vehicle like a BMW. Studies show that car thefts are on the rise, increasing by 20% in 2022. The top three models most likely to be stolen are from Dodge, Land Rover, and BMW. 

Every time you start your vehicle, the CAS Module creates a new, random BMW key code. Then, it synchronizes that code with your vehicle's Engine Control Unit (ECU), which is called a DME (digital motor electronics) in gas engines, and a DDE (digital diesel electronics) in diesel models. 

Signs of a Faulty System

Most of the time, your CAS Module won't break down completely overnight. Instead, it will begin to give you signals that something's wrong, such as:

  • A key fob that suddenly doesn't work
  • Difficulty starting your vehicle
  • Issues with your central locking system
  • Alarm activation issues
  • Warning lights or messages on your dashboard

If anything seems amiss, it's important to take your BMW to a local repair shop immediately. The CAS module is an important module in a BMW and MINI vehicles. 

Let's discuss some of the most common issues a little further, and the key signs associated with each one. 

Common CAS Module Fault Codes

Unless you're a trained and experienced mechanic, you might not know what's going on with your CAS Module. Even if you do think you've figured it out, we still recommend letting an expert take a look to make sure you're safe on the road. 

Some of the different fault codes they might see include:

  • A0C0 CAS: Terminal 15 output 3
  • CAS 14: Door Open F/R
  • CAS 15: Door Open F/L
  • CAS 16: Door Open R/L
  • CAS 17: Door Open R/R
  • CAS 18: Bonnet open
  • CAS 19: Boot open
  • CAS 21: Ignition problem, depress brake
  • CAS 22: Starter Problem
  • CAS 38: Wrong Remote Key
  • CAS 40: Press Brake to Start
  • CAS 65: Key Battery Low, change key
  • CAS 66: Remote Control/Key Fault
  • CAS 67: Remote Control/Key Battery Discharged
  • CAS 68: Remote Key Stationary Function Battery Low
  • CAS 186: ELV Steering Lock Fault
  • CAS 187: ELV Steering Lock Active, move the steering wheel
  • CAS 205: Remote Key not Present
  • CAS 206: Engine Start on Next Press
  • CAS 208: Comfort Access Deactivated
  • CAS 209: Remote Key in Vehicle, Locking not possible
  • CAS 217: No Remote Control
  • CAS 303: Depress Clutch to Start
  • CAS 335: Ignition Switched On
  • CAS 347: Position R/N/D Not Possible
  • CAS 348: Engage Park Before Leaving Vehicle
  • CAS 349: Engage Park Before Switching Ignition Off
  • CAS 413: Steering Column Unlocked

These are only a few of the fault codes you might see on your CAS Module. There are hundreds in all, and correcting the issue can be a complicated process.

Some of these are relatively self-explanatory. For instance, CAS 65 lets you know that your key battery is running low, and it's time to either change it or order a replacement. However, not all of them are as straightforward to address. 

Let's review some of the top fault codes listed above, and what they mean. 

Common Signs that BMW / MINI CAS Unit Hardware needs a Repair:

If a combination for the following fault codes are present in your BMW or MINI CAS module, it typically indicates that the hardware has failed. Our team offers a CAS module repair service for the following codes: 

  • A0A9 - CAS: Control Unit Fault: This code suggests a fundamental problem with the CAS module itself, potentially affecting communication with other vehicle systems or its ability to manage access and authorization functions properly.

  • A0B4 CAS: Engine Start, Starter Operation: Indicates issues with the starter operation signal. The CAS unit's failure to properly manage or send the start signal to the starter motor could result in the engine not cranking or starting.

  • A0BE CAS: Terminal 15 Output 1: Terminal 15 is related to the ignition switch's "on" position, powering up the vehicle's electrical systems. A fault here suggests problems with the power supply to essential vehicle components when the ignition is on.

  • A0BF CAS: Terminal 15 Output 2: Similar to A0BE, this fault code points to issues with another circuit powered by Terminal 15, affecting the vehicle's ability to energize secondary systems necessary for operation.

  • A0C0 CAS: Terminal 15 Output 3: Again, this code indicates a problem with the power distribution from Terminal 15, specifically affecting a third circuit or system within the vehicle.

These faults typically appear when the vehicle is hot inside and is a known problem for MINI vehicles. 

Key Fob Doesn't Work

Does your BMW seem to not be accepting your key? If your key fob suddenly stops unlocking or locking your doors, your CAS might be faulty. The same applies if you insert the key into the ignition and the engine doesn't start. 

Another problem you might be encountering is a mismatched key. If the key code in your CAS Module gets out of sync with the code stored in your vehicle's DME or DDE, this can occur. A repair specialist can reset the CAS under the correct module to solve the issue. 

Difficulty Starting Vehicle

It can be disheartening to get in the car and notice that it won't crank up. Or, it might start for a while and then begin to stall. 

If your engine turns over but doesn't start, two issues might be affecting your CAS Module: water damage or overvoltage. Both of these problems can have a direct effect on your engine. In most cases, drivers will need to completely replace and reprogram the Module for it to work. 

Central Locking System Issues

The central locking system is an integral part of your vehicle's safety and performance. If it stops working or only works part of the time, it could indicate a CAS Module fault. 

Alarm Activation Issues

You expect your alarm to work in the event of a theft or emergency. You don't want it to go off on its own for no viable reason! If yours sounds at random or doesn't activate when someone tampers with your vehicle, the CAS Module could be impaired. 

Warning Lights and Messages

This is one sign you can't afford to ignore. If your dashboard begins to display warning lights or messages about your CAS Module, take your BMW to a local repair shop as soon as possible. 

CAS Issue (A0C0)

Your CAS Module is normally responsible for alerting you if there's something wrong with your BMW. However, in some instances, the Module itself might be experiencing a malfunction.

If this happens, the most common fault code is A0C0:Terminal 15 Output 3. This code could indicate a disruption to the CAS power supply. Terminal 15 refers to the line that runs from the CAS to your vehicle's starter. If you see Terminal 15 codes, this means that the start button was pressed, but the line didn't activate. 

If the CAS Module fails, it will usually require a repair or replacement unit. Experts can typically perform repairs if corrupted software on the unit is the only issue. Often, this happens due to a failure to perform a required software update or when adding additional keys with the wrong tools. 

On the other hand, if the physical unit is damaged, a replacement CAS unit is most likely in order. This can happen from water damage, decay, or another force. 

Door Open Codes (CAS 14-17)

If you see a fault code that reads CAS 14 through CAS 17, this signals that there's a door-open alert. If your doors are open or even slightly ajar, closing them tightly should resolve the issue. However, you may also see this alert even if everything is securely closed. 

In that case, the issue could be with the lock actuator on the affected door. When the fault codes are reading a short or line disconnection, this is often what's behind the problem. 

Bonnet/Boot Open (CAS 18 and 19)

The same logic that applies to Door Open Codes also applies here. If the CAS is notifying you that the bonnet (front hood) or boot (back trunk) is open or ajar, check those closures first. If you don't see anything out of place, the issue could be with the latch sensors or actuators. 

Ignition Problem (CAS 21)

If there's a problem with your ignition, Fault Code 21 will display. Often this occurs because drivers have their foot on the brake when trying to start their vehicle. Depressing the brake should solve the issue, but it may require a more extensive repair. 

Another issue with your ignition could again be traced back to BMW CAS Terminal 15. If you can start your car but the display panel is blank, you might see a message such as IKE Voltage Supply Terminal 15, Faulty. In this case, you may need to replace your ignition switch. 

Starter Problem (CAS 22)

A fault code of CAS 22 signals that there's an issue with your starter motor, and the engine cannot restart. The message should alert you not to stop your engine, but take your BMW to the nearest repair shop immediately. 

Comfort Access Issue (CAS 208)

BMW's Comfort Access system is the brand's industry-leading keyless entry system. It's designed to detect when you're approaching your vehicle. Once it knows you're close, it will automatically unlock your doors and get your engine ready so you can start it with just one button. 

If you've activated Comfort Access on your BMW, the unlocked doors will open when you simply touch the handle. In addition, the controls will remember your preferred seating position and other interior features, automatically adjusting them as you get closer. If you see the CAS 208 fault code, there's an issue with this system.

This might mean there's a problem with the power supply going to the controls. Or, you may have accidentally deactivated it. Your repair team can address the issue and make the necessary adjustments.  

Position R/N/D Error (CAS 347)

Any time you get behind the wheel, you naturally need the reverse (R), neutral (N), and drive (D) functions to be available. If you see fault code CAS 347, they might not be operable. It may be necessary to activate the emergency release for the selector lever.

Often, an issue with one of the solenoid valves is to blame for this error, but an expert can diagnose the problem.

How Does Our Mail-In Repair Service Work?

As you can see, this is only a small sample of the many fault codes you may encounter with your BMW CAS Module. With so many issues at work, it's nearly impossible to identify or address all of them yourself.

That's where we come in. 

Our Mail-In Testing Services allow you to remove your original CAS, KEY, and DME, and then mail the components to us. Our expert mechanics will get to the bottom of the issue and recommend the appropriate repairs or replacement units. Possible next steps may include:

  • Testing
  • Repairs
  • Replacement or cloning

We run full diagnostic tests on all CAS Modules, using actual vehicles so we can get the most accurate reading. Once testing is complete, we'll send you a comprehensive report of all our findings. Our service is 100% plug-and-play, which means there's no additional coding required. 

If we don't find any fault at all, we'll send your Module back to you! Return shipping is included in our service price, so there's not an additional fee for this service. If we do need to repair or replace your unit, we can complete most of our work in one to three days!

The exact timeline will depend on the availability of your required parts and the extent of damage to your CAS unit. For more detailed projects, repairs can take between five and 10 days. Still, offered at a fraction of the OEM repair price, our Mail-In Testing Service is a smart investment for any BMW driver. 

Understand and Fix Your BMW CAS Module Fault Codes

Investing in a BMW means driving in style for the rest of your life. However, part of being a responsible driver is staying on top of any issues lurking beneath your hood. 

The BMW CAS Module is a central component of your vehicle, and you need to know when it's not working properly. Thankfully, there are fault codes to help you understand and address any problems that occur. Instead of trying to decipher them yourself, trust our team to the task!

At The ECU Pro, we offer comprehensive mail-in testing services to keep your CAS Module in excellent working order. Contact us today to learn more or schedule a service!

Mail in automotive electronic repair services 

The ECU Pro offers an affordable mail-in repair service for automotive electronics. To have your unit repaired, simply remove the part and mail it to us. Our professional team will either test, repair, or clone your unit. 

Our team has over 30 years experience in automotive electronic repairs. We specialize in German vehicles such as BMW, Mercedes and Mini. Our main focus is engine control unit repairs ( ECU, PCM or DME). Our state of the art facility has over 30 test vehicles to ensure that all parts are tested in actual vehicles before being returned to our clients.

    Most of the services we provide is plug and play and doesn't require any additional coding. 

      Select your vehicle

      Can't find your vehicle or service?

      Finding brands