AutoCodes – Generic – U0008

U0008 Code - High Speed CAN Communication Bus (-) High

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: U0008 indicates High Speed CAN Communication Bus (-) High.
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 15,741

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 U0008 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 U0008 - High Speed CAN Communication Bus (-) High - AutoCodes.com — U0008 Code - High Speed CAN Communication Bus (-) High

What does this mean?

What are the Possible Causes of the DTC U0008?

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 U0008?

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 U0008 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 U0008 code?

Need more information on how to fix the U0008 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0008 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U0008 Ford — High Speed CAN Communication Bus (-) High
U0008 Lincoln — High Speed CAN Communication Bus (-) High
U0008 Mercury — High Speed CAN Communication Bus (-) High

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 U0008 Code

1. What are the common symptoms of OBDII code U0008 (High Speed CAN Communication Bus (-) High)?

Symptoms may include issues with the vehicle's network communication system, such as intermittent or complete loss of communication between control modules.

2. What can cause OBDII code U0008 to trigger?

This code may be triggered by damaged or faulty wiring, connectors, or control modules within the high-speed CAN communication network.

3. How can I diagnose the underlying cause of OBDII code U0008?

Diagnosis typically involves inspecting the wiring harness, connectors, and control modules associated with the high-speed CAN bus for any signs of damage, corrosion, or loose connections.

4. Is it safe to continue driving with OBDII code U0008 present?

It is not recommended to drive the vehicle with this code present, as it may lead to further communication issues between critical control modules.

5. How can I repair OBDII code U0008?

Repairing this code often involves repairing or replacing damaged wiring, connectors, or control modules within the high-speed CAN network.

6. Can a DIY enthusiast fix OBDII code U0008 at home?

While some basic troubleshooting steps can be performed at home, diagnosing and repairing this code may require advanced diagnostic tools and expertise, making it more suitable for professional technicians.

7. What are the potential consequences of ignoring OBDII code U0008?

Ignoring this code may lead to further electrical communication issues within the vehicle, potentially impacting its overall performance and safety.

8. How much does it typically cost to repair OBDII code U0008?

The cost of repairing this code can vary depending on the extent of the damage and the specific components that need to be repaired or replaced. It is advisable to consult with a professional technician for an accurate estimate.

9. Can extreme weather conditions contribute to triggering OBDII code U0008?

Yes, extreme weather conditions, such as excessive heat or moisture, can potentially damage the wiring or connectors associated with the high-speed CAN communication network, leading to the triggering of this code.

10. Is OBDII code U0008 a common issue in specific vehicle makes or models?

This code can occur in various vehicle makes and models that are equipped with a high-speed CAN communication network. However, some models may have a higher incidence of this issue due to specific design or manufacturing factors.