OBD-II diagnostic trouble code
U0101Stop driving

Lost Communication with TCM

The network has lost contact with the transmission control module specifically, which can leave the transmission stuck in a single gear (limp mode) until resolved.

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Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.

Frequently asked questions

Can I drive with U0101?

No — U0101 is flagged as a code where you should stop driving and get the car checked as soon as possible. Continuing to drive risks further damage or a safety issue.

How much does it cost to fix U0101?

The cost varies too much by cause and vehicle to give a single figure here — a diagnosis will narrow it down.

What causes U0101?

AS
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief
Code names compiled from open SAE/ISO references; explanations and repair guidance are original editorial content
Last verified: 09 Jul 2026 · Our methodology