After a failed ISTA-P programming procedure, a BMW CAS3++ module may become corrupted, preventing the vehicle from starting due to an incorrect synchronization between the CAS and DME rolling codes. In such cases, the Xhorse VVDI Key Tool MIDI can be used with the ISTAP Repair function to restore the CAS data and help recover normal vehicle operation.
Why Does the CAS Need Repair?
The issue occurred after the CAS module was programmed using ISTA-P. Following the unsuccessful programming, the vehicle could no longer start.
ISTA detected an EVS synchronization and communication fault between the CAS and DME, suggesting that the required security data exchange between the two modules had been disrupted.
The repair process involved restoring a clean CAS EEPROM dump containing the correct ISN and VIN information, followed by running the ISTA-P CAS repair procedure to restore proper communication and synchronization.
Prepare the CAS Module
1. Read the CAS EEPROM with VVDI PROG
Use VVDI PROG to read the CAS EEPROM data and prepare a clean dump containing the vehicle’s ISN and VIN information.
2. Write the Clean EEPROM Dump Back
Write the prepared clean EEPROM dump back to the CAS module. The ZB number displayed on the CAS module is 9278746.
Run ISTAP Repair
- Turn on the power supply, connect the CAS module, insert the key into the ignition, and follow the device prompts.
- On Key Tool MIDI, go to Immo Programming → BMW → Select from System → CAS3/CAS3+ Immo System → ISTAP Repair → Start Programming, then select “Use the Known CAS Series Number to Repair” and enter CAS ID: 9278746.
- Follow the prompts and press OK. The device will erase the flash and perform the programming. The repair took approximately 5 minutes in this case.
Check ISTAP Repair Compatibility
Before performing an ISTAP repair, it is important to verify the CAS part number and software version, as not all CAS modules are supported.
In our test, the CAS module with SW 22.5 was successfully repaired. CAS versions around SW 21 and newer were also found to be suitable for the tested procedure. However, older software versions, such as SW 12.5, may not be supported and compatibility can vary depending on the specific CAS part number.
Other tested part numbers, including 9237046 and 9226238, were not confirmed to support this repair method.
The CAS identification screen provides important details, including the hardware version, software version, diagnostic version, and index. The successfully tested module was equipped with C4 hardware.
Always check the CAS information and confirm compatibility before starting the repair procedure.
Check for EEPROM Issues
The Key Tool MIDI may detect EEPROM or key-file errors during operations such as EEPROM uploading, dealer key generation, or signature verification. If the EEPROM data becomes corrupted during ISTA or KFP programming, use the EEPROM repair function to restore the data before proceeding with the related operation.
Reinstall the Repaired CAS
Once the ISTAP repair process is complete, reinstall the repaired CAS module back into the vehicle. The key had already been generated using the Key Tool MIDI and saved to slot 1.
After reinstalling the repaired CAS, the vehicle started successfully and the main vehicle functions operated normally.
Skype: xhorsevvdi.com
Whatsapp: https://wa.me/8613983756354
Whatsapp: 
Skype: