AutoCodes – Generic – U0023

U0023 Code - Low 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: U0023 indicates Low 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 8,435

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 U0023 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 U0023 - Low Speed CAN Communication Bus (+) High - AutoCodes.com — U0023 Code - Low Speed CAN Communication Bus (+) High

What does this mean?

What are the Possible Causes of the DTC U0023?

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 U0023?

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 U0023 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 U0023 code?

Need more information on how to fix the U0023 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0023 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 U0023 Code

1. What are the common symptoms of OBDII code U0023 (Low Speed CAN Communication Bus (+) High)?

- Common symptoms include issues with the vehicle's communication systems, dashboard warning lights, and potential communication failures between various modules.

2. What can cause the OBDII code U0023 to trigger?

- The code U0023 is typically triggered by problems with the low-speed CAN communication bus, such as wiring issues, faulty modules, or poor connections.

3. How can I diagnose the OBDII code U0023?

- Diagnosis usually involves using a scan tool to retrieve the code, checking the wiring and connections related to the low-speed CAN bus, and testing the modules for proper functioning.

4. Are there any DIY repair tips for fixing the U0023 code?

- DIY repair tips may include checking and repairing any damaged wiring, ensuring proper connections, and resetting the fault codes to see if the issue reoccurs.

5. Can the OBDII code U0023 lead to other problems in the vehicle?

- Yes, unresolved issues related to the low-speed CAN communication bus can lead to communication failures between critical vehicle modules, affecting overall performance and functionality.

6. Is it safe to continue driving with the U0023 fault code present?

- It is recommended to address the U0023 code promptly to prevent potential communication failures between modules and ensure the vehicle's systems operate correctly.

7. How much does it typically cost to repair the U0023 fault code?

- The cost of repairing the U0023 fault code can vary depending on the underlying cause, but it may involve expenses related to diagnostics, parts replacement, and labor.

8. Can a faulty battery or alternator cause the U0023 fault code?

- While a faulty battery or alternator can potentially cause communication issues in a vehicle, the U0023 fault code is more commonly associated with problems specific to the low-speed CAN communication bus.

9. Will disconnecting the battery reset the U0023 trouble code?

- Disconnecting the battery may temporarily clear the fault code, but it is important to diagnose and address the underlying issue causing the U0023 code to prevent it from reoccurring.

10. How long does it take to repair the U0023 fault code?

- The repair time for the U0023 fault code can vary based on the complexity of the underlying issue, the availability of parts, and the expertise of the technician performing the repairs.