- Faulty Engine Control Module (ECM)
- Engine Control Module harness is open or shorted
- Engine Control Module circuit poor electrical connection
- Engine Control Module (ECM) not configured
When is the code detected?The control module is not configured properly.
- Engine Light ON (or Service Engine Soon Warning Light)
U0400 DescriptionSome control modules are constantly receiving information from other control modules through serial data communication network. The invalid data code will be set when a receiving control module detects a discrepancy in information it receives from another control module causing its integrity to be questioned. The symptom byte listed in the DTC Descriptor is for engineering reference only. No external circuit diagnosis is involved.
U0400 Information for specific makes
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U0400 CommentsHelp us improve AutoCodes.com. Leave a comment below or tell us if the information above help you fix the code. What are the symptoms on your vehicle for the U0400 code? Have you replaced any parts?
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