top of page
GM U1040 Code – Network Communication Voltage Fault
Limited
Safe to drive :
GM vehicles only
Applies only to :
Not applicable to :
This explanation does NOT apply to other manufacturers.
Medium
Severity level :
When Does This Code Appear on the Vehicles
GM U1040 occurs when BCM detects voltage irregularity affecting module communication.
What This Code means on the Vehicles
Indicates network fault caused by low or fluctuating battery voltage.
Why This is different from a generic OBD2 Code
Generic OBD-II scanners cannot identify voltage-induced module communication errors.
Common Situations That Trigger This Code
Weak battery; Loose battery terminals; Corroded connections.
What Will NOT Fix This Code
Replacing sensors unrelated to voltage supply.
How to Clear This Code on Vehicles
Inspect battery and connections; verify voltage stability; clear code via OEM tool.
Related Manufacturer Specific Codes
GM U1000; GM U1010
bottom of page