After performing engine optimization, the following errors are 95% likely to occur, which are only visible after loading any diagnostics. These are engine unit software checksum - ECM. The original checksum of the engine unit is stored in the memory of the central vehicle module - CEM. At start-up, this unit checksum is compared with the current motor unit checksum, which concludes that this sum is not the same. Subsequently, both the motor unit and the central module declare an error that the software is "not compatible". These errors have no effect on the function of the car or on the result of the technical inspection at the MOT. This checksum error can be corrected by software, but the D5T5 does not make it clear that it is clear that there is modified software in the car if any engine system fault is resolved.

Typical error messages after performance optimization:

CEM-U030100 - Software incompatibility with ECM/PCM
ECM-U032700 - Software incompatibility with Vehicle Security Control Module
ECM-U032200 - Software Incompatibility with Body Control Module
ECM-7700 - Engine control module (ECM). Communication fault
CEM-3A00 - ECM Software. Faulty Signal
CEM-1F00 - ECM Software. Faulty Signal.
ECM-C301 - Control module, faulty software check sum ECM

These errors have NO effect on the function of the vehicle or the MOT and do not need to be addressed in any way - they are only an indication of the modified ECM software.