Carlexica

U0101: Lost Communication With TCM

A generic network and communication trouble code, same meaning on every brand.

Fix now, drive carefully

Minimal driving - losing the transmission computer can mean sudden limp mode.

$120 - $1,800
typical repair range
65
NHTSA complaints mention this code
77,520
median mileage when reported, mi

Symptoms

  • Transmission stuck in one gear (limp)
  • Shift indicator blank or wrong
  • Multiple warning lights

Likely causes, most common first

  1. CAN bus wiring to the TCM
  2. TCM power or ground loss
  3. Failed transmission module

Read U0101 yourself before paying for diagnosis

A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.

What is going on and how it gets diagnosed

U0101 means other modules lost communication with the transmission control module. The transmission itself may be healthy - the computer running it has gone silent, and the default response is a single fixed gear.

As with all network codes, wiring and connector diagnosis beats parts-swapping. Water intrusion into module connectors is a recurring theme worth mentioning to the shop if your car has flood or deep-puddle history.

Repair options and cost

Network and power diagnosis$120 - $300
Wiring repair$150 - $800
TCM replacement + programming$600 - $1,800

Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.

Owner reports mentioning U0101

“The contact owns a 2020 Chevrolet Silverado 1500. The contact stated that while driving at approximately 40 MPH, the vehicle shuddered and downshifted independently. No warning lights illuminated. Additionally, an OBD2 diagnostic scan retrieved diagnostic trouble codes: U0146, U0101, and U0100. A local dealer was contacted; however, the vehicle was not diagnosed or repaired because the VIN was not included in any recall. Additionally, the contact related the failure to NHTSA Campaign Number: 24V797000 (Power Train). The manufacturer was not made aware of the failure. The failure mileage was approximately 84,000.”2020 Chevrolet Silverado 1500 · Jul 2026 · 84,000 mi
“I have about 08/1825 had the throttle body replaced on my vehicle which assisted with the problem temporarily. Then the problem started again 09/20/25 the car act like it's stalling while driving and can't see what hear the vehicle is in. The car is not getting any signal to the engine as I have been advised the TCM is faulty. There was a code of U0101.”2012 Chevrolet Impala · Sep 2025
“The vehicle's TCM has apparently failed as evidenced by CEL code "U0101", low power ("limp mode"), hard shifting, no gear selection indicator, and extremely slow acceleration. Vehicle is currently available for inspection, but will be receiving a replacement TCM soon. Myself and others' safety was put at risk due to my the vehicle's inability to continue through an intersection at a reasonable rate. The problem has not been reproduced by a dealer/service center, nor has it been inspected by anyone since the incident. The aforementioned warning lamp that indicated the issue appeared upon starting the vehicle, which drove normally for the first 11 miles.”2012 Chevrolet Silverado 2500 · Apr 2025
Show 7 more owner reports
“The contact owns a 2019 Chevrolet Equinox. The contact stated that the check engine warning light was illuminated. The vehicle was taken to an Advanced Auto Parts where a diagnostic test was performed and DTC U0101 and P12A6 were retrieved. The vehicle was then taken to a local independent mechanic where the vehicle was diagnosed, and the contact was informed that the transmission control module was faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 108,533.”2019 Chevrolet Equinox · Mar 2025 · 108,533 mi
“Dangerous lurching and sometimes with not engage. Other Nissan models have the same problem. The diagnostic code is U0101 bad communication between TCM and Vehicle.”2015 Nissan Frontier · Sep 2024
“Code U0101 is set. Unable to communicate with TCM. Troubleshooted and found TCM is bad. Removed necessary components for tcm replacement. Removed the tcm/valve body assembly and replaced. Replaced necessary gaskets and reinstalled necessary components. Set transmission fluid level to specifications per procedure. Dealer advised they stock 3 TCM at all times due to many failures and demands of TCM.”2015 Chevrolet Sonic · Aug 2024
“Mar11th Tcm failed gears got stuck while driving use bypass switch to park car no longer starts code U0101 popped up and ECS light came on”2009 Hyundai Veracruz · Mar 2024
“Transmission Control Module malfunction. The AT light came on and the car made a jerking motion and a clunking noise. It lost power and would not shift which is very dangerous in moving traffic. It put me at risk for getting hit by another vehicle not expecting the abrupt change in speed by my vehicle. The check engine light is now lit up. There were no warning lights before the vehicle's transmission malfunctioned. A code came up on the vehicle when tested. U0101 lost communication with TCM. From what I have read, researched, and have been told this issue is very common for certain years of Mazda 3's including mine.”2013 Mazda MAZDA3 · Nov 2023
“Car went crazy one day while behind the wheel everything malfunctioned then car shut off and won't start again. I could of easily got into an accident had there been any other vehicles around. Kids were scared. Codes come up as U0100,U0140,U0101,C0242,B0081-0F,B0081-71,B1370-01,B1370-06,U0155-00,U0170-00,P0856-00.”2008 Cadillac CTS · Jul 2023
“Power steering stability trak doors locking making clicking sound all this shows up on dash and the car feels like it is accelerating and then jerks slows down and a big sound putting it into gear and a code that says U0101”2014 Chevrolet Impala · Jul 2023

Cars that report U0101 most often

Based on mentions of this code in NHTSA owner complaints.

2019 Chevrolet Silverado 15003 mentions in complaints2020 Chevrolet Silverado 15002 mentions in complaints2014 Chevrolet Impala2 mentions in complaints2025 GMC Sierra 15002 mentions in complaints2012 Ford Focus2 mentions in complaints2005 Chevrolet Cobalt2 mentions in complaints2014 Ford Focus2 mentions in complaints2016 Chevrolet Colorado2 mentions in complaints2013 Mazda MAZDA31 mentions in complaints2014 Dodge Charger1 mentions in complaints2019 Ram 15001 mentions in complaints2013 Buick Regal1 mentions in complaints

Frequently asked questions

Can I drive with U0101?

Minimal driving - losing the transmission computer can mean sudden limp mode.

How much does it cost to fix U0101?

Typical US repair costs range from $120 for the simplest fix (network and power diagnosis) to $1,800 in the worst case. The right number depends on which cause your car has - see the causes list.

Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.