The owner of this Mercedes-Benz Sprinter reported a significant loss of power, even though earlier checks with Launch and Autel diagnostic tools had shown no faults. An ECU inspection found that fault reporting had been altered in the control-unit software, preventing the diagnostic equipment from displaying current information.

The ECU was read on the bench with Flex, its existing software was checked, and the necessary changes were made, including restoring fault-code reporting. The work also covered EGR and DPF control settings. After the ECU was refitted, a new diagnostic scan showed a fault related to the first cylinder’s glow plug, which had not appeared before.

The Sprinter was then road-tested under load. It drove without the earlier lack of power. The video provides no dyno figures and does not establish why fault reporting had been changed in the previous software.