OBD Guide

U1866

Battery Energy Control Module Lost Communication With Body Control Module

U1866 is an OBD-II diagnostic trouble code meaning: Battery Energy Control Module Lost Communication With Body Control Module. Common causes: open or short circuit in the communication circuit, poor contact in module connectors. Estimated repair cost: $6–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$6–167 (est.)

Symptoms

  • Flashing or failure of lighting equipment
  • Window failure
  • Errors in the operation of the dashboard
  • Problems starting the car
  • Incorrect battery level readings

Causes

  • Open or short circuit in the communication circuit
  • Poor contact in module connectors
  • Battery management module malfunction
  • Body control module problems
  • Wiring harness damage

How to Fix

  1. Check the integrity of the wiring between the modules
  2. Inspect and clean the contacts in the connectors
  3. Check power and ground of modules
  4. Read fault codes of all modules
  5. Replace damaged components if necessary

Related codes

FAQ

What does the U1866 code mean?

U1866 is an OBD-II diagnostic trouble code that indicates: Battery Energy Control Module Lost Communication With Body Control Module

What causes a U1866 error code?

The most common causes of U1866 include: Open or short circuit in the communication circuit; Poor contact in module connectors; Battery management module malfunction; Body control module problems.

How do I fix a U1866 diagnostic trouble code?

To fix U1866: Check the integrity of the wiring between the modules. Inspect and clean the contacts in the connectors. Check power and ground of modules. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U1866?

Yes, but get it checked soon

How much does it cost to fix U1866?

The estimated repair cost for U1866 is $6–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat