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GM U1201 Code – ECM Invalid Data
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 U1201 occurs when BCM receives invalid data from ECM.
What This Code means on the Vehicles
Indicates ECM sending incorrect or corrupted signals on Class 2 bus.
Why This is different from a generic OBD2 Code
Generic scanners cannot report module-specific data errors.
Common Situations That Trigger This Code
ECM malfunction; Wiring issues; Firmware mismatch.
What Will NOT Fix This Code
Replacing unrelated modules or sensors.
How to Clear This Code on Vehicles
Inspect ECM and wiring; clear code via Tech2/OEM.
Related Manufacturer Specific Codes
GM U1200; GM U1202
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