OBD-II DTC · SAE J2012
U019D
Lost Communication With Direct Ozone Reduction Catalyst Temperature Sensor
What U019D means
U019D is a standard SAE J2012 powertrain diagnostic trouble code with the defined meaning: Lost Communication With Direct Ozone Reduction Catalyst Temperature Sensor. 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 U019D is active
Catalyst efficiency below threshold MIL, post-cat lambda mirror behaviour after a de-cat downpipe, P0420 / P0430 immediately after exhaust upgrade.
Can this code be suppressed via ECU tuning?
Suppressible at the calibration level. Required when fitting a de-cat downpipe or running a leaner catalyst. Off-road only.
How to remove U019D with Softechpro V5
Recommended service: CAT OFF. Step-by-step workflow:
- Open Softechpro V5 and load the ECU file.
- Select CAT OFF / O2 Mirror — Softechpro neutralises the post-catalyst lambda comparison logic that throws this code.
- Save the patched .bin (checksum auto-recomputed).
- Flash and reset adaptations. The MIL clears within 2-3 drive cycles.
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.