Citroën factory diagnostics include DiagBox and the earlier Lexia software. DiagBox is shared with Peugeot and DS; older supported Citroëns can require Lexia within the diagnostic environment. Select by VIN and confirm the interface, software version and access. PSA DiagBox guide; SILIM legacy software guide.
Earlier Citroën systems include ELIT and the Lexia/Proxia family; see early Peugeot and Citroën diagnostic tools for documented examples and sources.