05/08/2026
UK heavy-vehicle testing is catching up with modern electronics.
From February 2026, DVSA assessors began visual ADAS checks on HGVs and PSVs — looking at cameras/sensors and related warning lamps (monitoring stage, not yet part of the annual test result). At the same time, the wider aftermarket debate is about independents keeping real access to diagnostics, coding and repair data as vehicles become software-defined.
For workshops still running Mercedes Euro 6 trucks and buses day-to-day, that means careful diagnosis when the Common Powertrain Controller (CPC3) is implicated:
1) Confirm the stored codes and live symptoms (no throttle, intermittent pedal, no-start, CAN/drive-bus issues).
2) Check power supply, earths, foot-control wiring and related CAN links before swapping boxes.
3) Identify the fitted CPC3 by the label (e.g. ELECTRONIC CPC 3 / part family on the unit).
4) Prefer repairing the original module where viable — avoids unnecessary coding/programming paths and wrong-used-unit risk.
Common codes seen with CPC3 faults include ADFFEE, ACFFEE and EEF7ED (A3 Driving Control Unit / CPC defective). Codes alone are not a remote diagnosis — the vehicle still needs proper workshop testing.
Essex Recons Mercedes CPC3 repair (postal return, min. 24-month warranty):
https://www.essexrecons.com/shop/hgv/mercedes-cpc-3-repair-service/
Guide: https://www.essexrecons.com/mercedes-cpc-3-failure-and-repair/