AutoCodes – Generic – U0071

U0071 Code - Vehicle Communication Bus 'E' (-) 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: U0071 indicates Vehicle Communication Bus 'E' (-) 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 4,607

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 U0071 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 U0071 - Vehicle Communication Bus 'E' (-) High - AutoCodes.com — U0071 Code - Vehicle Communication Bus 'E' (-) High

What does this mean?

What are the Possible Causes of the DTC U0071?

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 U0071?

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 U0071 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 U0071 code?

Need more information on how to fix the U0071 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0071 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 U0071 Code

1. What does the OBDII code U0071 mean?

U0071 indicates an issue with the Vehicle Communication Bus 'E' (-) being in a high voltage state, disrupting communication between control modules.

2. What are common symptoms of code U0071?

Common symptoms include warning lights on the dashboard (e.g., ABS or traction control), erratic vehicle behavior, and loss of communication with certain modules.

3. What causes code U0071 to be triggered?

The code can be caused by a faulty wiring harness, damaged connectors, a short circuit, or a malfunctioning control module.

4. How can I diagnose code U0071?

Diagnose the code by inspecting wiring and connectors for damage, checking the bus voltage with a multimeter, and using a scan tool to pinpoint affected modules.

5. Can code U0071 affect vehicle performance?

Yes, it can lead to issues with systems relying on the communication bus, such as stability control, anti-lock brakes, and powertrain functions.

6. How do I fix the U0071 code?

Repair tasks may include replacing damaged wiring, cleaning or repairing connectors, or replacing a defective control module.

7. Is code U0071 a serious issue?

Yes, it can be serious as it affects communication between vehicle systems, potentially compromising safety and drivability.

8. Can I drive with the U0071 code active?

Driving with this code is not recommended, as critical systems may be impaired, increasing the risk of accidents.

9. What tools are needed to address the U0071 code?

Youâ€™ll need a scan tool, multimeter, and possibly wiring repair kits to diagnose and fix the issue.

10. Will clearing the U0071 code fix the problem?

Clearing the code may temporarily remove the warning, but the underlying issue must be resolved to prevent the code from returning.

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