AutoCodes – Toyota – U0140 2018 Toyota RAV4

U0140 2018 Toyota RAV4 Code - Lost Communication with Main Body ECU

Quick Answer

The Controller Area Network (CAN) is a standard bus system in vehicles that enables the connection of automotive devices without the need for a host computer. Common causes include Faulty Controller Area Network (CAN) Communication System, Faulty Main Body ECU, Main Body ECU harness is open or shorted. 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 2018 Toyota RAV4 indicates Lost Communication with Main Body ECU.
Common causes: Common causes include Faulty Controller Area Network (CAN) Communication System, Faulty Main Body ECU, Main Body ECU harness is open or shorted.
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 251

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 26, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U0140 2018 Toyota RAV4 Description

The Controller Area Network (CAN) is a standard bus system in vehicles that enables the connection of automotive devices without the need for a host computer. The exchange of operating information and commands among devices is facilitated by pre-programmed information about the required message exchange on the serial data circuits. Communication is carried out using two dedicated wires, known as CAN high and CAN low, with both lines carrying 2.5V when the CAN bus is in idle mode. During the transmission of data bits, the CAN high line increases to 3.75V while the CAN low drops to 1.25V, creating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Main Body ECU has not been received.

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OBDII Code U0140 2018 Toyota RAV4 - Lost Communication with Main Body ECU - AutoCodes.com — U0140 2018 Toyota RAV4 Code - Lost Communication with Main Body ECU

What does this mean?

What are the Possible Causes of the DTC U0140 2018 Toyota RAV4?

Faulty Controller Area Network (CAN) Communication System
Faulty Main Body ECU
Main Body ECU harness is open or shorted
Main Body ECU circuit poor electrical connection

How to Fix the DTC U0140 2018 Toyota RAV4?

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 does this mean?

Code Tech Notes

When there are problems with the way different systems in a vehicle communicate with each other using a technology called Controller Area Network (CAN) communication, Diagnostic Trouble Codes (DTC) are displayed. These codes can be caused by issues with the main bus or branch of the communication network, or with the Electronic Control Units (ECUs) and sensors that make up the different systems. If you see code for both the CAN communication problems and internal or power source problems at the same time, you should focus on fixing the internal or power source problems first.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0140 2018 Toyota RAV4 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 2018 Toyota RAV4 Code

1. What does the OBDII code U0140 on a 2018 Toyota RAV4 mean?

The U0140 code indicates a communication problem between the vehicle's main body electronic control unit (ECU) and other modules.

2. What are common symptoms of U0140 code in a 2018 Toyota RAV4?

Common symptoms include issues with power windows, door locks, interior lights, and other body control functions not working properly.

3. What are some possible causes of the U0140 code in a 2018 Toyota RAV4?

Possible causes include damaged wiring or connectors, a faulty main body ECU, issues with other control modules, or software glitches.

4. How can I diagnose the U0140 code in my 2018 Toyota RAV4?

Diagnosing the U0140 code typically involves using a professional OBDII scanner to retrieve the trouble codes and then performing a thorough inspection of the wiring, connectors, and control modules involved.

5. Can I still drive my 2018 Toyota RAV4 with the U0140 code?

It is not recommended to drive the vehicle with the U0140 code present, as it may affect important body control functions and compromise overall safety.

6. How can I repair the U0140 code in my 2018 Toyota RAV4?

Repairing the U0140 code may involve repairing or replacing damaged wiring, connectors, or the main body ECU, as well as addressing any underlying issues with other control modules.

7. Is it possible to reset the U0140 code in a 2018 Toyota RAV4 without fixing the underlying issue?

Resetting the code without addressing the underlying issue may temporarily clear the warning light, but the problem will likely return if the root cause is not fixed.

8. Can a DIY enthusiast fix the U0140 code in a 2018 Toyota RAV4?

While some simple checks like inspecting wiring and connectors can be done by a DIY enthusiast, diagnosing and repairing the U0140 code may require professional tools and expertise.

9. How much does it cost to fix the U0140 code in a 2018 Toyota RAV4?

The cost of fixing the U0140 code can vary depending on the specific cause of the issue, but it may involve expenses for parts replacement, labor, and diagnostic services.

10. Are there any recalls or technical service bulletins related to the U0140 code in the 2018 Toyota RAV4?

It's recommended to check with your local Toyota dealership or service center for any recalls or technical service bulletins related to the U0140 code in the 2018 Toyota RAV4.