Module Communication Trouble Codes: List & Fixes
Module communication codes, such as U0100 (lost communication with the engine control module) or U0121 (lost communication with the ABS module), mean a module did not receive expected messages on the data bus. Start with the basics: battery voltage, grounds, fuses and connectors, especially where water can get in. Aftermarket accessories spliced into the wiring can also disturb the network.
43Codes
3.1Average severity
33%High or critical
5%DIY-friendly
Severity distribution
Most viewed
U0105
Network
The PCM lost contact with the separate module that fires the injectors, common on diesel…
High
U0101
Network
The engine computer and other modules stopped hearing from the transmission control module.
High
U0121
Network
Other modules stopped receiving data from the ABS module, so ABS and stability control are off.
Moderate
U0001
Network
A module found the high-speed CAN network itself misbehaving, not just one silent module.
High
U0122
Network
Other modules lost contact with the stability control computer, so ESC and traction control…
Moderate
U0418
Network
Brake-control data such as pedal position or brake-assist status looks implausible to another…
High
All codes (33)
U1000
Nissan · Network
A Nissan control module couldn't send or receive CAN messages for about 2 seconds or longer.
Moderate
U1064
Chevrolet · Network
Other modules stopped hearing the body control module on an older GM's Class 2 data line.
Moderate
U1900
Ford · Network
A Ford module stopped receiving messages it expects from another module on the CAN network.
Moderate