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Engine-Codes – Generic – U0071

U0071 Code - Vehicle Communication Bus 'E' (-) High

Quick Answer

The diagnostic code U0071 indicates a problem with the Vehicle Communication Bus 'E' (-) High. Common causes include Faulty wiring or connections in the communication bus system, Short circuit in the communication bus circuit, Corrosion or damage to communication bus connectors. 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 Faulty wiring or connections in the communication bus system, Short circuit in the communication bus circuit, Corrosion or damage to communication bus connectors.
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.
What is this?
Table of contents Created and updated by William Orellana on Aug 19, 2024
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Code U0071 Description

The diagnostic code U0071 indicates a problem with the Vehicle Communication Bus 'E' (-) High. The Vehicle Communication Bus is a network that allows various modules within the vehicle to communicate with each other. When this code is triggered, it means that there is a high voltage condition detected on the communication bus 'E'. This can lead to issues with the vehicle's electronic systems, causing malfunctions in various components such as the engine control module, transmission control module, ABS system, and more. If left unresolved, this issue can lead to further electrical failures and potentially affect the overall performance and safety of the vehicle.

OBDII Code U0071 - Vehicle Communication Bus 'E' (-) High
U0071 Code - Vehicle Communication Bus 'E' (-) High

Common Causes of U0071

  1. Faulty wiring or connections in the communication bus system
  2. Short circuit in the communication bus circuit
  3. Corrosion or damage to communication bus connectors
  4. Failed communication bus module
  5. Electrical interference from aftermarket accessories

Symptoms of U0071

  1. Check engine light illuminated on the dashboard
  2. Loss of communication with various vehicle modules
  3. Erratic behavior of electronic components (e.g., power windows, door locks)
  4. Difficulty starting the vehicle
  5. Transmission shifting issues

How to Fix U0071

  1. Diagnose the issue using a scan tool to pinpoint the exact cause of the high voltage condition on the communication bus
  2. Inspect the wiring and connections in the communication bus system for any damage or corrosion
  3. Test the communication bus module for proper operation and replace if necessary
  4. Clear the fault code and retest the system to ensure the issue has been resolved
  5. Perform a final road test to confirm that the vehicle's electronic systems are functioning correctly

Cost to Fix U0071

The cost of repairing the Vehicle Communication Bus 'E' (-) High issue can vary depending on the exact cause of the problem and the labor rates in your area. On average, you can expect to pay anywhere from $200 to $500 for parts and labor. Keep in mind that diagnostic time and labor rates at auto repair shops can fluctuate, so it's advisable to consult with a professional to get a more accurate estimate for your specific vehicle.

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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 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?

You’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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