What it means
Generic U0124: modules stopped receiving the lateral acceleration sensor module’s frames (part of ESC inputs). Usually HS-CAN, sometimes integrated with the yaw sensor on a common node. OBD-Codes.com
Typical symptoms
- ESC/traction lights; possible ADAS limitations; co-sets with U0123/U0126. RepairPal.com
Why it sets
- Timeout on required messages from the G-sensor node; same HS-CAN physical-layer sensitivities apply (opens/shorts/termination errors). NHTSA Static
Common root causes
Power/ground loss at sensor; HS-CAN wiring/termination faults; connector corrosion (floorpan/tunnel areas); internal module bus-off; aftermarket interference. OBD-Codes.com
Professional diagnostics
Global scan & topology → sensor offline? → verify feeds/grounds → HS-CAN checks (~60 Ω, 2.5 V bias) → segment isolation → connector/pin-drag → software/part last. NHTSA Static
Verified fixes
Restore power/grounds; repair bus wiring; correct terminations; repin/clean connectors; remove add-ons; update/replace & initialize; clear, drive, re-scan.
Sources
- OBD-Codes – U0124 (definition & diagnostics). OBD-Codes.com
- RepairPal – U0124 (symptoms/causes). RepairPal.com
- GM/ACDelco – HS-LAN Tips (~60 Ω reference). NHTSA Static
- TroubleCodes.net – U0124 (additional context; practitioner-level). troublecodes.net