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ElectricalSeverity High: diagnose before driving on

U0140Lost Communication With Body Control Module

What it means

A control module stopped receiving messages from the body control module on the data bus (CAN). The body control module may be without power or ground, or the bus wiring to it is faulty.

Symptoms

  • Lights, locks or wipers not working
  • Several warning lights at once
  • Other modules may store related codes

Common causes

  • No power or ground at the body control module
  • CAN wiring open, shorted or corroded (CAN-H / CAN-L)
  • Low battery voltage during cranking
  • Failed body control module

What to check first

  1. Check fuses, supplies and grounds at the body control module
  2. Measure CAN-H to CAN-L resistance with the battery disconnected (about 60 Ω on most cars)
  3. Scope CAN-H and CAN-L for a clean mirrored signal
Can I drive with U0140? Not recommended. U0140 can lead to stalling, limp mode or engine damage; diagnose it before driving further.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind U0140

CAN bus networkWiring, typical values, multimeter and scope tests

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U0140: questions and answers

What does U0140 mean?

U0140: Lost Communication With Body Control Module. A control module stopped receiving messages from the body control module on the data bus (CAN). The body control module may be without power or ground, or the bus wiring to it is faulty.

What are the symptoms of U0140?

Lights, locks or wipers not working. Several warning lights at once. Other modules may store related codes.

What causes U0140?

No power or ground at the body control module. CAN wiring open, shorted or corroded (CAN-H / CAN-L). Low battery voltage during cranking. Failed body control module.

How do you diagnose U0140?

1. Check fuses, supplies and grounds at the body control module 2. Measure CAN-H to CAN-L resistance with the battery disconnected (about 60 Ω on most cars) 3. Scope CAN-H and CAN-L for a clean mirrored signal

Can I drive with U0140?

Not recommended. U0140 can lead to stalling, limp mode or engine damage; diagnose it before driving further.