AutoCodes – Chevrolet – U18A7 Chevrolet

U18A7 Chevrolet Code - Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Power Supply Transformer, Power Supply Transformer harness is open or shorted, Power Supply Transformer 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: U18A7 Chevrolet indicates Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus.
Common causes: Common causes include Faulty Power Supply Transformer, Power Supply Transformer harness is open or shorted, Power Supply Transformer 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 10,150

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 Jun 08, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U18A7 Chevrolet Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device. The Diagnostic Trouble Code (DTC) will set a supervised periodic message that includes the transmitter device availability that has not been received.

OBDII Code U18A7 Chevrolet - Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus - AutoCodes.com — U18A7 Chevrolet Code - Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18A7 Chevrolet?

Faulty Power Supply Transformer
Power Supply Transformer harness is open or shorted
Power Supply Transformer circuit poor electrical connection

How to Fix the DTC U18A7 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 U18A7 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 U18A7 Chevrolet Code

1. What are common symptoms of the U18A7 OBDII code in a Chevrolet?

- Common symptoms include loss of communication with powertrain control modules, illuminated warning lights on the dashboard, and issues with vehicle performance.

2. What can cause the U18A7 code to appear in a Chevrolet?

- The U18A7 code is often triggered by a communication error with the power supply transformer on the powertrain expansion CAN bus, which can be caused by wiring issues, faulty connectors, or a defective power supply transformer.

3. How can I diagnose the U18A7 code in a Chevrolet?

- Diagnosing the U18A7 code typically involves checking the wiring and connectors related to the power supply transformer, performing a visual inspection for any visible damage, and using a diagnostic scanner to pinpoint the communication error.

4. Is it safe to continue driving with the U18A7 code present in a Chevrolet?

- It is not recommended to continue driving with the U18A7 code present, as it can lead to further electrical issues and potential performance problems with the vehicle.

5. How can the U18A7 OBDII code be repaired in a Chevrolet?

- Repairing the U18A7 code usually involves fixing any wiring or connector issues, replacing the faulty power supply transformer if necessary, and clearing the code with a diagnostic scanner.

6. Can a DIY enthusiast fix the U18A7 code issue in a Chevrolet?

- While some basic troubleshooting steps can be performed by a DIY enthusiast, resolving the U18A7 code may require specialized tools and expertise, so it is recommended to consult a professional mechanic for proper diagnosis and repair.

7. Are there any preventive measures to avoid the U18A7 code in a Chevrolet?

- Regularly inspecting the wiring and connectors in the powertrain expansion CAN bus system, addressing any electrical issues promptly, and following the manufacturer's maintenance schedule can help prevent the U18A7 code from appearing.

8. Will resetting the OBDII system clear the U18A7 code in a Chevrolet?

- Resetting the OBDII system may temporarily clear the U18A7 code, but it is essential to address the underlying communication error with the power supply transformer to prevent the code from reappearing.

9. How long does it typically take to repair the U18A7 code in a Chevrolet?

- The repair time for the U18A7 code can vary depending on the extent of the issue, but it may take a few hours to a full day to diagnose, repair, and clear the code.

10. Can the U18A7 code affect other systems in the Chevrolet?

- Yes, the U18A7 code can affect other systems in the vehicle that rely on communication with the power supply transformer, potentially leading to additional error codes and malfunctions.