AutoCodes – Buick – U0140 Buick

U0140 Buick Code - Lost Communication With Body Control Module

Quick Answer

Modules connected to the high speed General Motor Local Area Network (GMLAN) 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: U0140 Buick indicates Lost Communication With Body Control Module.
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 15,415

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 Apr 01, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0140 Buick Description

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules 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 module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Body Control Module (BCM) has not been received.

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OBDII Code U0140 Buick - Lost Communication With Body Control Module - AutoCodes.com — U0140 Buick Code - Lost Communication With Body Control Module

What does this mean?

What are the Possible Causes of the DTC U0140 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 U0140 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 U0140 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 U0140 Buick Code

1. What does the OBDII code U0140 mean on a Buick?

U0140 indicates that the vehicle's Body Control Module (BCM) has lost communication with other control modules on the network.

2. What are the common symptoms of the U0140 code in a Buick?

Symptoms may include non-functional power windows, locks, wipers, interior lights, or other electrical features controlled by the BCM. Warning lights may also appear on the dashboard.

3. What causes the U0140 code to appear on a Buick?

Possible causes include a faulty BCM, damaged wiring or connectors, a blown fuse, or issues with the vehicle's communication network.

4. Can a weak battery trigger the U0140 code on a Buick?

Yes, a weak or failing battery can cause voltage drops that disrupt communication between modules, potentially triggering the U0140 code.

5. How do I diagnose the U0140 code on my Buick?

Start by checking the battery voltage, inspecting the BCM wiring and connectors for damage or corrosion, and verifying continuity in the CAN bus communication lines.

6. Is it safe to drive a Buick with the U0140 code?

It depends on the severity of the symptoms. If critical systems like lights or wipers are affected, itâ€™s best to address the issue before driving.

7. How can I fix the U0140 code on my Buick?

Repairs may include fixing damaged wiring, replacing a blown fuse, reprogramming, or replacing the BCM if itâ€™s faulty.

8. Does the U0140 code require BCM replacement in every case?

No, the BCM doesnâ€™t always need replacement. Often, the issue can be resolved by repairing wiring or addressing power supply problems.

9. Can clearing the U0140 code solve the problem?

Clearing the code might temporarily remove it, but if the underlying issue isnâ€™t fixed, the code will return.

10. How much does it cost to repair the U0140 code on a Buick?

Costs vary depending on the issue. Simple fixes like replacing a fuse or repairing wiring may cost under $100, while BCM replacement and programming can exceed $500.