We were contacted by a client with a complaint that their Mercedes Benz W222 S350 diesel would no longer crank after it being idle for a few weeks.
Upon visual inspection, it was found that a warning message was displayed saying "Eng. start not possible" - this is generally due to underlying issues with the adblue/Scr system.
Before reaching any conclusions, we ran a diagnostic scan on all modules and found a fault in the CDI/engine control unit saying there was no communication to the SCR/ADBLUE control module and that the starter was inhibited due to this fault.
We performed wiring integrity checks which checked out and found that the Adblue control module itself was faulty, the client was informed and decided instead to do a complete sofwtare Adblue/SCR delete in the engine control unit saving time and money as it would have taken a few weeks before the replacement control module could arrive.
After taking permission from the client to remove the engine control unit from the vehicle, the software was read out from the control unit and modified to work as though the vehicle had no adblue/scr.
After this, the engine control unit was mounted and plugged back on the vehicle, the "Eng. start not possible" was no more and the vehicle started right up.
The client was delighted to have his vehicle running without needing any parts or extensive labor.