DTC codes / U05xx · Network communication / U0577
U0577 is a communication fault where the lighting driver control module D reports data that the main body computer judges invalid or out of range. The computer has received a message from that module but the message content fails its internal plausibility or checksum checks, so it flags the data as untrustworthy rather than treating it as a total loss of communication.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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