A start-authorisation warning after ECU refitting needs the repair and installation records considered together. It does not by itself establish that the keys need replacing or that the repaired ECU is unusable.
Contact the repairer with evidence
Provide the exact warning, scan, ECU label and work reference. State whether the same original unit was returned and which installation or setup steps were completed. Retain all original keys and related modules.
Do not attempt unrelated data writes, security resets or bypass files before discussing the result with the repairer. Such changes can complicate assessment and obscure the returned condition. The specialist should explain what data was retained, what was verified on the bench and whether the vehicle requires a supported authorised setup procedure. If another garage performed the installation, coordinate one clear report so that compatibility, connections and start authorisation are investigated without contradictory changes from multiple parties.
Related help
Browse all fault guides or use the vehicle module finder to prepare your enquiry. Include the vehicle, symptoms, complete fault codes and any previous test results. Assessment scope and compatibility must be confirmed before booking or sending a unit.