OBD Guide
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U18B8

Lost Communication With Body Control Module On High Speed CAN Bus

U18B8 is an OBD-II diagnostic trouble code meaning: Lost Communication With Body Control Module On High Speed CAN Bus. Common causes: open or short circuit in the can bus wiring, body module (bcm) malfunction. Estimated repair cost: $56–222.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–222 (est.)

Symptoms

  • Power windows don't work
  • Problems with central locking
  • Lighting malfunctions
  • Dashboard malfunctions
  • Occurrence of other CAN bus errors

Causes

  • Open or short circuit in the CAN bus wiring
  • Body Module (BCM) Malfunction
  • BCM power or ground problems
  • Damage to connectors or corrosion of contacts
  • Malfunction of other modules in the CAN network

How to Fix

  1. Check the integrity of the CAN bus wiring
  2. Check body module power and grounding
  3. Inspect connectors and contacts for damage
  4. Scan other modules for errors
  5. If necessary, replace the body module

Related codes

U18A8U18C8U18D8

FAQ

What does the U18B8 code mean?

U18B8 is an OBD-II diagnostic trouble code that indicates: Lost Communication With Body Control Module On High Speed CAN Bus

What causes a U18B8 error code?

The most common causes of U18B8 include: Open or short circuit in the CAN bus wiring; Body Module (BCM) Malfunction; BCM power or ground problems; Damage to connectors or corrosion of contacts.

How do I fix a U18B8 diagnostic trouble code?

To fix U18B8: Check the integrity of the CAN bus wiring. Check body module power and grounding. Inspect connectors and contacts for damage. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U18B8?

Yes, but get it checked soon

How much does it cost to fix U18B8?

The estimated repair cost for U18B8 is $56–222. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat