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DTC codes / U01xx · Lost communication with a control module / U0147

U0147Lost Communication With Gateway 'B'

U0147 means the modules on one of the vehicle's controller area network (CAN) buses have stopped receiving messages from a central gateway module designated 'B'. The computer that set the code detected that the gateway's periodic heartbeat or data messages went missing for longer than the allowed timeout, so it flagged the communication loss.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaLost communication with a control module

Symptoms you may notice

  • Warning light or message on the dash, often with no other noticeable change in how the car drives
  • Multiple unrelated warning lamps lit at once, such as stability control, airbag, and tire pressure lights
  • Some electrical features stop working, like power windows, climate control, or the radio
  • The engine may crank but not start, or the vehicle may fail to start at all if the gateway is on the starting bus
  • Intermittent no-start or stalling that comes and goes with temperature or vibration
  • A scan tool may fail to communicate with several modules at the same time

Common causes, most likely first

  1. Loose, corroded, or damaged ground connection at the gateway module or its mounting point
  2. Faulty gateway module 'B' itself, often due to internal failure or water intrusion
  3. Damaged or chafed CAN bus wiring between the gateway and the modules that reported the loss
  4. Blown fuse or poor power feed to the gateway module, including a weak battery or charging system
  5. A shorted or failed module on the same bus pulling the network down and blocking gateway messages
  6. Corroded pins or water in a connector along the gateway's communication path
  7. Software or configuration mismatch after a module replacement or battery service

How to diagnose and fix it

  1. Scan all modules for codes and record which modules report U0147 and which bus they sit on
  2. Check battery voltage and charging system output, then inspect and clean the gateway module's ground and power connections
  3. Inspect the gateway module connectors and the CAN wiring for corrosion, chafing, or pushed-out pins
  4. Measure CAN bus resistance and voltage at the gateway connector to confirm the bus is healthy
  5. Disconnect suspect modules one at a time to see if communication returns, isolating a module that is pulling the bus down
  6. If wiring and power are good, substitute a known-good gateway module or perform the required configuration and relearn procedure
  7. Clear codes and road-test, then recheck that no communication codes return after a full drive cycle

Gateway faults that mimic other failures

  • A weak or failing battery is a frequent hidden cause of U0147 because the gateway module drops offline during cranking and logs the loss before voltage recovers.
  • Technicians often replace the gateway module first, but a chafed CAN wire or a shorted module on the same bus will set the same code again immediately after the new part is fitted.
  • U0147 can appear after a windshield replacement or body repair if water reaches a connector or a ground point near the gateway, so always check for moisture history.
  • The code does not always mean the gateway is dead; it can be set by a single module on the bus that keeps transmitting errors and crowding out the gateway's messages.
  • On some vehicles the gateway is integrated into the body control module, so a body control module fault or configuration issue can present as a gateway communication loss.

Can I keep driving with U0147?

If the car starts, runs, and drives normally, you can usually drive it to a shop for diagnosis, but avoid long trips and keep in mind that other systems may stop working without warning. If the engine will not start or multiple safety systems are disabled, do not drive and have the vehicle towed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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