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GM U1100 Code – Module Gateway Sync Lost
Limited
Safe to drive :
GM vehicles only
Applies only to :
Not applicable to :
This explanation does NOT apply to other brands.
Medium
Severity level :
When Does This Code Appear on the Vehicles
GM U1100 shows when a module loses sync with the gateway.
What This Code means on the Vehicles
Module unable to communicate properly with gateway module.
Why This is different from a generic OBD2 Code
Generic OBD-II cannot detect gateway-specific sync issues.
Common Situations That Trigger This Code
Gateway module failure; Wiring harness issues; Aftermarket devices.
What Will NOT Fix This Code
Replacing unrelated modules.
How to Clear This Code on Vehicles
Diagnose module sync, wiring, and gateway; clear via Tech2/OEM.
Related Manufacturer Specific Codes
GM U1101; GM U1102
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