AutoCodes – Generic – U0066

U0066 Code - Vehicle Communication Bus 'E' (+) Open

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Diagnosis of this Diagnostic Trouble Code (DTC) is accomplished via the vehicle symptom(s), Check for more codes, Faulty Control Module. 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: U0066 indicates Vehicle Communication Bus 'E' (+) Open.
Common causes: Common causes include Diagnosis of this Diagnostic Trouble Code (DTC) is accomplished via the vehicle symptom(s), Check for more codes, Faulty Control Module.
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 2,751

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 Mar 29, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0066 Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating 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 supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U0066 - Vehicle Communication Bus 'E' (+) Open - AutoCodes.com — U0066 Code - Vehicle Communication Bus 'E' (+) Open

What does this mean?

What are the Possible Causes of the DTC U0066?

Diagnosis of this Diagnostic Trouble Code (DTC) is accomplished via the vehicle symptom(s)
Check for more codes
Faulty Control Module
Control Module harness is open or shorted
Control Module circuit poor electrical connection

How to Fix the DTC U0066?

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 U0066 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.

Need more information about the U0066 code?

Need more information on how to fix the U0066 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0066 code diagnosed by a professional: Find a repair shop in your area

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 U0066 Code

1. What are the common symptoms of OBDII code U0066?

- Common symptoms include issues with the vehicle's communication system, such as loss of communication between control modules, warning lights on the dashboard, and difficulties diagnosing other codes.

2. What does the OBDII code U0066 indicate?

- This code indicates a malfunction related to the communication bus 'E' on the vehicle, specifically an open circuit.

3. What are the possible causes of OBDII code U0066?

- Possible causes include damaged wiring or connectors in the communication bus 'E' circuit, faulty control modules, a blown fuse, or a software issue within the vehicle's system.

4. How can I diagnose the OBDII code U0066?

- Diagnosing this code typically involves using a diagnostic scanner to retrieve the code, checking for any related codes, inspecting the wiring and connectors in the communication bus 'E' circuit, and testing control modules for proper functionality.

5. Can I still drive my vehicle with OBDII code U0066 present?

- It is generally not recommended to drive the vehicle with this code present, as it may lead to further communication issues and potential safety concerns. It is advisable to address the underlying problem as soon as possible.

6. How can I repair OBDII code U0066?

- Repairing this code may involve repairing or replacing damaged wiring or connectors in the communication bus 'E' circuit, addressing any issues with control modules, ensuring proper power and ground connections, and clearing the code with a diagnostic tool.

7. Is it possible to prevent OBDII code U0066 from occurring?

- While some causes of this code may be related to wear and tear, ensuring regular maintenance of the vehicle's electrical system, avoiding water damage to connectors, and promptly addressing any warning lights or communication issues can help prevent this code from occurring.

8. Can a DIY enthusiast fix OBDII code U0066?

- Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to address the simpler causes of this code, such as checking and repairing wiring or connectors. However, more complex issues may require professional diagnosis and repair.

9. Will resetting the OBDII code U0066 make it go away permanently?

- Simply resetting the code without addressing the underlying issue will not make it go away permanently. It is essential to diagnose and repair the root cause of the code to prevent it from reoccurring.

10. How long does it typically take to repair OBDII code U0066?

- The repair time for this code can vary depending on the specific cause and complexity of the issue. Simple fixes like reconnecting loose wiring may take a short time, while diagnosing and repairing control module issues could be more time-consuming and may require professional assistance.