Code result
U0101
Lost Communication with TCM
High severity
What it means
The ECU has stopped receiving messages from the transmission control module. The transmission falls into limp-home mode (typically locked in 3rd or 4th gear), the speedometer may stop working, and shift adaptation freezes.
Is it safe to drive?
No — stop driving
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly.
Most likely causes
TCM unpowered or grounded poorly
highOne of the most commonly reported causes for this code — check this first.
CAN wiring to TCM broken
mediumA plausible cause — test and verify before replacing parts.
Gateway module routing CAN messages incorrectly
lowLess common, but worth ruling out after the more likely causes.
Related help
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