× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network

U0121 Diagnostic Trouble Code Discussion for January 2025

Lost Communication With EBCM


Note: This is a professional automotive technician's resource.
Vehicle Owners: If you are seeking an automotive repair professional to service your vehicle, visit the iATN Repair Shop Finder.

Trouble Ticket Help Requests for DTC U0121
Help Request Posted
2025 Chevrolet 2500 HD 6.6L MIL Lamp on, MIL and various on
U0121: Lost Comm w ECBM. ... [...] (gasoline powered 6.6 w/alison auto trans; 2500 hd 2x4 reg. cab fleetside pickup). Motologic has no info for truck or Vin (2023 model year wiring different?) New Truck (662 mi) came for upfitting (200 gallon pest control tank). Mounted to b...
January 10, 2025