AutoCodes – Buick – U18B8 Buick

U18B8 Buick Code - Lost Communication With Body Control Module On High Speed CAN Bus

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Body Control Module (BCM), Body Control Module harness is open or shorted, Body Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: U18B8 Buick indicates Lost Communication With Body Control Module On High Speed CAN Bus.
Common causes: Common causes include Faulty Body Control Module (BCM), Body Control Module harness is open or shorted, Body Control Module circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 595

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 09, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U18B8 Buick Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device. The Diagnostic Trouble Code (DTC) will set a supervised periodic message that includes the transmitter device availability that has not been received.

OBDII Code U18B8 Buick - Lost Communication With Body Control Module On High Speed CAN Bus - AutoCodes.com — U18B8 Buick Code - Lost Communication With Body Control Module On High Speed CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18B8 Buick?

Faulty Body Control Module (BCM)
Body Control Module harness is open or shorted
Body Control Module circuit poor electrical connection

How to Fix the DTC U18B8 Buick?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U18B8 Buick code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U18B8 Buick Code

What does the OBDII code U18B8 mean on a Buick?

1. The U18B8 code indicates a loss of communication between the Body Control Module (BCM) and the high-speed CAN bus network, which is vital for information exchange between vehicle systems. 2.

What are common symptoms of the U18B8 code in a Buick?

Symptoms may include malfunctioning interior electronics (such as power windows or locks), warning lights on the dashboard, intermittent electrical issues, or a failure to start. 3.

What causes the U18B8 code to appear in a Buick?

Common causes include a faulty Body Control Module (BCM), damaged or corroded CAN bus wiring, loose electrical connections, or issues with related modules on the network. 4.

Can a weak battery trigger the U18B8 code?

Yes, a weak or failing battery can cause communication errors on the CAN bus, including triggering the U18B8 code. 5.

How can I diagnose the U18B8 code in my Buick?

Start by checking the battery voltage, inspecting CAN bus wiring and connectors for damage or corrosion, and using a scan tool to check for other related codes or module communication issues. 6.

Can I drive my Buick with the U18B8 code active?

Driving with the U18B8 code is not recommended, as it can lead to unpredictable behavior of critical systems and may pose safety risks. 7.

How is the U18B8 code fixed in a Buick?

Repairs may involve repairing or replacing damaged wiring, securing loose connections, reprogramming or replacing the BCM, or addressing issues with other modules on the CAN bus. 8.

How much does it cost to fix the U18B8 code in a Buick?

Repair costs can vary widely, ranging from $100 for minor wiring repairs to $500 or more if the BCM needs replacement or reprogramming. 9.

Can a software update resolve the U18B8 code?

In some cases, a software update for the Body Control Module or other related modules may resolve the communication issue, but this depends on the specific circumstances. 10.

What tools are needed to troubleshoot the U18B8 code in a Buick?

You'll need a diagnostic scan tool capable of reading BCM and CAN bus data, a multimeter to test electrical connections, and possibly an oscilloscope to monitor CAN bus signals.