Code U0101?

Tiny
MARKUSCHAMP
  • MEMBER
  • 2014 BUICK LA CROSSE
  • 2.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 196,000 MILES
From one day to the next my car lost acceleration power from the stop position. It now takes 3 times as long to pick up speed from stop position. Dash says service Stabil Trak and check engine light on. Also, when I put the car in reverse it clunks, and the reverse camera is no longer working. Last thing is that auxiliary battery is making a humming sound that was never there before.
Wednesday, April 30th, 2025 AT 8:44 AM

2 Replies

Tiny
AL514
  • MECHANIC
  • 5,246 POSTS
Hello, U codes are module/network communications codes. So, if a U0101 was stored in the engine computer (ECM/PCM) and a traction control light is on, including these other symptoms you mentioned, there is most likely going to be other codes stored in other modules. So, a full system scan should be done to see what other modules have for codes in them, it might be that something is affecting the data bus network causing these issues. At least one module is setting a communications code, and most vehicles these days have multiple networks built into them.

It also looks like this is a hybrid vehicle, correct? So having a shop scan the vehicle with a capable scan tool would be the next step, you don't want to mess around with any high voltage wiring that hybrids carry, it's enough voltage to harm a person or worse. The high voltage wires are bright orange to avoid them. Theres a few technical service bulletins listing this code which do mention the transmission control modules harness and ground locations being checked at contact locations where the harness may have rubbed threw and possibly be making contact with the engine block. That would explain why the reverse camera may not be working as well, since it's triggered on by being put into Reverse.

So, the transmission control module might not be communicating correctly, or another module on its network is sending out corrupt data packets, affecting all the modules on the high-speed data bus. When network faults like this occur, it usually affects more than one system in the vehicle, so that's probably why you are experiencing multiple issues at once. But do avoid the high voltage system if you are not trained to work on them.
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Wednesday, April 30th, 2025 AT 3:46 PM
Tiny
AL514
  • MECHANIC
  • 5,246 POSTS
This was one of TSBs (technical service bulletin) on a U0101 code setting, the others stated the same information about wiring harness issues. here is a guide as well to doing a full system scan for other codes setting in additional modules.

https://www.2carpros.com/articles/can-scan-controller-area-network-easy
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Wednesday, April 30th, 2025 AT 3:55 PM

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