CAN network

U0146 — Lost Communication with Gateway Module C

Severity: medium Drive with care, to a shop

What U0146 means

Control modules constantly share messages over CAN buses. Gateway Module C routes data between the high-speed and low-speed buses, acting as a translator between groups of modules. U0146 means a module stopped receiving messages from the gateway, or the gateway stopped responding, so network communication was lost.

Symptoms

  • Several U-codes set at the same time
  • Multiple warning lights on
  • Several systems stop working
  • Functions of the affected module are unavailable
  • Instrument cluster shows wrong data or goes dead

Possible causes

  1. Failed gateway module
  2. Open, shorted or chafed CAN bus wiring
  3. Aftermarket alarm or accessory spliced into the gateway wires
  4. Corroded connectors or terminals
  5. A faulty control module loading down the bus
  6. Power supply or ground fault at the gateway or another module

How to diagnose

  1. Run a full-module scan and map which modules respond and which do not
  2. Look for aftermarket alarms or accessories tapped into the CAN wires
  3. Check battery voltage and terminal condition
  4. Inspect harnesses and connectors at the gateway and affected modules for chafing, moisture or corrosion
  5. Test power and ground at the gateway and the silent modules
  6. Measure CAN bus resistance and voltages at the diagnostic connector
  7. Disconnect suspect modules one at a time, only following a documented procedure
  8. Clear codes and see if the fault returns

Common fixes

  • Repair open, shorted or corroded CAN wiring
  • Replace damaged connectors and terminals
  • Remove or correctly rewire aftermarket equipment on the bus
  • Restore power and ground to the affected module
  • Replace or reprogram the gateway, or the module that is loading the bus

Questions and answers

What does U0146 mean?

It means communication with Gateway Module C was lost. That module passes messages between CAN buses, so modules cannot share data properly without it.

Can I drive with U0146?

Only briefly and with care, since key functions may fail. If brake or ABS lights come on or limp mode starts, have the car towed.

Do I need to replace the gateway right away?

No. Wiring, connectors, power, grounds or aftermarket devices are more common causes. Check those first before blaming the gateway.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.