OBD-II DTC · SAE J2012
C00A4
Driveline Control Module Rear Differential Unit B Control Circuit Driver
What C00A4 means
C00A4 is a standard SAE J2012 powertrain diagnostic trouble code with the defined meaning: Driveline Control Module Rear Differential Unit B Control Circuit Driver. This is the OEM-agnostic definition; specific manufacturer interpretation may add detail (subsystem, bank, sensor location) but the core meaning is consistent across all OBD-II compliant vehicles since 1996.
Common symptoms when C00A4 is active
Multiple module MILs at once, U-code family lit, intermittent module dropouts (especially after a battery disconnect or coding change).
Can this code be suppressed via ECU tuning?
Whether this code is safe to suppress depends on the underlying cause. Diagnose first, suppress only after confirming the mechanical issue is benign or rectified.
How to remove C00A4 with Softechpro V5
Recommended service: DTC OFF (communication branch) — fix wiring first. Step-by-step workflow:
- Communication codes often mean a bad CAN line, dead module, or coding mismatch. Fix the bus first.
- If a coded-out module legitimately remains absent (e.g. removed AdBlue heater), Softechpro V5 DTC OFF can suppress the U-code referencing the missing module.
- Load .bin, select DTC OFF + communication group, save, flash.
Softechpro V5 supports 1,400+ ECU firmwares across Bosch (EDC15, EDC16, EDC17, MD1, MG1, ME7, MED17), Siemens / Continental (SID, SIMOS, EMS), Delphi (DCM, DDC), and Magneti Marelli platforms.