AutoCodes – Chevrolet – U1023 Chevrolet

U1023 Chevrolet Code - Lost Communications With Hybrid Control Module

Quick Answer

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Common causes include Faulty Hybrid Control Module (HCM), Hybrid Control Module harness is open or shorted, Hybrid Control Module circuit poor electrical connection. 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: U1023 Chevrolet indicates Lost Communications With Hybrid Control Module.
Common causes: Common causes include Faulty Hybrid Control Module (HCM), Hybrid Control Module harness is open or shorted, Hybrid Control Module circuit poor electrical connection.
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 623

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 Apr 22, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1023 Chevrolet Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for the state of health monitoring/node alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that module node alive message. Each module on the class 2 serial data circuit is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a Diagnostic Trouble Code (DTC) U1023 is set.

OBDII Code U1023 Chevrolet - Lost Communications With Hybrid Control Module - AutoCodes.com — U1023 Chevrolet Code - Lost Communications With Hybrid Control Module

What does this mean?

What are the Possible Causes of the DTC U1023 Chevrolet?

Faulty Hybrid Control Module (HCM)
Hybrid Control Module harness is open or shorted
Hybrid Control Module circuit poor electrical connection

How to Fix the DTC U1023 Chevrolet?

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 U1023 Chevrolet 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.

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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 U1023 Chevrolet Code

1. What are the common symptoms of OBDII code U1023 in a Chevrolet related to "Lost Communications With Hybrid Control Module"?

The common symptoms include loss of power in the hybrid system, poor fuel efficiency, and potential stalling or rough idling of the vehicle.

2. What are some possible causes of OBDII code U1023 in a Chevrolet indicating "Lost Communications With Hybrid Control Module"?

Possible causes could be a faulty hybrid control module, damaged wiring or connectors, a weak battery, or issues with the CAN bus communication network.

3. How can I diagnose the OBDII code U1023 in a Chevrolet for "Lost Communications With Hybrid Control Module"?

Diagnosis involves using an OBDII scanner to retrieve the code, checking the hybrid control module for power and ground, inspecting the wiring for damage, and testing the communication network for connectivity issues.

4. Can I still drive my Chevrolet with the OBDII code U1023 indicating "Lost Communications With Hybrid Control Module"?

It is not recommended to drive the vehicle with this code active, as it can lead to further damage to the hybrid system and potentially unsafe driving conditions.

5. How can I repair OBDII code U1023 in a Chevrolet related to "Lost Communications With Hybrid Control Module"?

Repair methods may include replacing the hybrid control module, repairing damaged wiring or connectors, ensuring a strong battery connection, and addressing any communication network issues.

6. Are there any common mistakes to avoid when dealing with OBDII code U1023 in a Chevrolet indicating "Lost Communications With Hybrid Control Module"?

Avoid neglecting the issue, as it can lead to more severe problems with the hybrid system. It's also important not to overlook basic checks like battery health and wiring integrity.

7. Will resetting the OBDII code U1023 in a Chevrolet resolve the issue of "Lost Communications With Hybrid Control Module"?

Simply clearing the code without addressing the underlying problem will not resolve the issue. It's crucial to diagnose and repair the root cause to prevent the code from reoccurring.

8. How can I prevent OBDII code U1023 from appearing in my Chevrolet due to "Lost Communications With Hybrid Control Module" in the future?

Regular maintenance checks, including inspecting wiring, connectors, and the hybrid system components, can help prevent this code from appearing. Keeping the vehicle's battery in good condition is also important.

9. Is it safe to attempt DIY repairs for OBDII code U1023 in a Chevrolet indicating "Lost Communications With Hybrid Control Module"?

While some basic checks and maintenance tasks can be performed by DIY enthusiasts, complex repairs involving the hybrid system may require professional assistance to ensure safety and proper functioning.

10. How long does it typically take to repair OBDII code U1023 in a Chevrolet related to "Lost Communications With Hybrid Control Module"?

The repair time can vary depending on the specific issue causing the code, but it may take a few hours to a full day for diagnostics, parts replacement, and testing to ensure the problem is resolved effectively.