U0101 A module has stopped hearing from the transmission control module
13 owner reports and 276 manufacturer filings across 74 model years from Audi, Buick, Cadillac, Chevrolet and others.
Where U0101 shows up
Source: NHTSA manufacturer communications and complaintsShowing the 25 model years where U0101 appears most; it is on file for 74 in total.
A model year appears here because the code is named in its record, not because every one of these vehicles sets it. Counts are mentions in the federal files, not failure rates — nobody publishes the denominator.
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U0101 by make
The same record, one make at a time: the model years, bulletins and owner reports that name U0101 on that maker’s vehicles.
What it gets filed under
What owners said
Source: NHTSA complaint databaseOwners’ own words, one per nameplate, scrubbed of anything identifying. These are unverified reports filed with NHTSA — they are what was said, not a finding that it was true.
Stored codes show lost CAN communication among multiple modules: U0101, C1611, C1693, U0111, U0164, U0293, U042B, U1341
Car had to be towed to dealership a few days after services were completed, and was diagnosed at dealership, with an offline TCM, throwing a U0101 code
The diagnostic machine retrieved DTC: U0073, P0700, P25A2, U0101,U0129,U0146, U18D5, U18D7, U2413, U0073-00, U0100-00, U0140-00, U0151-00, U026A-00, U0420-00 and U0100
I did not tell them the vehicle had malfunctioned, throwing code U0101 and another code
I ran my scanner got a U0101 Loss communication to TCM (Transmission Control Module)
276 manufacturer filings name U0101. Start with what the maker wrote down.
A code names the test that failed, not the part. A bulletin that names it is often a diagnosis someone has already written down — quote its number at the service desk.
Manufacturer filings that name it
Source: NHTSA manufacturer communicationsService bulletins and campaigns whose filed summary names U0101.
- 21-016-25 REV. C Service bulletin2025-08-15 · Power Train
- Valve Body Replacement Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● U0101 - Lost Communication With The Transmission Control Module (TCM). ● U0402 - Implausible Data Received From TCM. ● U0418 - Implausible Data Received From Brake System Control Module 1. Customers may als
- 21-016-25 REV. B Service bulletin2025-08-07 · Power Train
- Valve Body Replacement Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● U0101 - Lost Communication With The Transmission Control Module (TCM). ● U0402 - Implausible Data Received From TCM. ● U0418 - Implausible Data Received From Brake System Control Module 1. Customers may als
- 9100641 Service bulletin2025-08-05 · Power Train
- Symptoms/Condition: Shifter reports loss communication AND NO OTHER MODULES report the condition. Diagnostic: Please make sure ONLY shifter reports loss communication. If there are other modules reporting loss communication, then follow the existing service procedure Repair Procedure: 1. Verify Complaint - ESM reports a Loss of Communication (LOC) DTC, but no other modules do. - If multiple module
- 21-016-25 REV. A Service bulletin2025-05-18 · Power Train
- "Valve Body Replacement Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● U0101 - Lost Communication With The Transmission Control Module (TCM). ● U0402 - Implausible Data Received From TCM. ● U0418 - Implausible Data Received From Brake System Control Module 1. Customers may al
- 21-016-25 Service bulletin2025-02-14 · Power Train
- "Valve Body Replacement Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● U0101 - Lost Communication With The Transmission Control Module (TCM). ● U0402 - Implausible Data Received From TCM. ● U0418 - Implausible Data Received From Brake System Control Module 1. Customers may a
- 21-016-25 Service bulletin2025-02-14 · Power Train
- "Valve Body Replacement Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● U0101 - Lost Communication With The Transmission Control Module (TCM). ● U0402 - Implausible Data Received From TCM. ● U0418 - Implausible Data Received From Brake System Control Module 1. Customers may a
What U0101 means
Source: SAE J2012 / OBD-IIA module has stopped hearing from the transmission control module.
A stored code names the test that failed, never the part that caused it. It is the starting point of a diagnosis, not its conclusion — the same code has several possible causes and the cheap one is not always right.
Common questions about U0101
Source: NHTSA files and the OBD-II standardCan I keep driving with U0101 stored?
Nobody can answer that from the code alone, and a site that does is guessing. A steady light means a fault was logged and the car should be checked soon; a flashing light means a severe misfire — slow down and get it seen as soon as possible, because severe misfire can quickly damage the catalytic converter. The safe read of this page is the mileage and the components, not permission.
Does a code mean the car is recalled?
No. Recalls are filed by campaign and matched by VIN, and none of them are triggered by a scan tool. If you want to know whether an open recall applies to one specific vehicle, check the VIN at nhtsa.gov/recalls — that is the only source that settles it.
Why do the counts here differ from other sites?
Because these are not estimates. Every number on this page is a count of documents in NHTSA's own files: manufacturer communications that name the code in their filed summary, and owner complaints that name it in the narrative. We do not model, weight or extrapolate them.
Will clearing the code fix it?
Clearing turns the light off and erases the freeze-frame data a technician would have used to work out what happened. If the condition is still there the code returns, usually within a few drive cycles, and the diagnosis now starts from less information than before.