AutoCodes – Chevrolet – U18A1 Chevrolet

U18A1 Chevrolet Code - Lost Communication With Coolant Temperature Control Module On High Voltage Energy Management CAN Bus

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Coolant Temperature Control Module, Coolant Temperature Control Module harness is open or shorted, Coolant Temperature 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: U18A1 Chevrolet indicates Lost Communication With Coolant Temperature Control Module On High Voltage Energy Management CAN Bus.
Common causes: Common causes include Faulty Coolant Temperature Control Module, Coolant Temperature Control Module harness is open or shorted, Coolant Temperature 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 742

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 U18A1 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 U18A1 Chevrolet - Lost Communication With Coolant Temperature Control Module On High Voltage Energy Management CAN Bus - AutoCodes.com — U18A1 Chevrolet Code - Lost Communication With Coolant Temperature Control Module On High Voltage Energy Management CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18A1 Chevrolet?

Faulty Coolant Temperature Control Module
Coolant Temperature Control Module harness is open or shorted
Coolant Temperature Control Module circuit poor electrical connection

How to Fix the DTC U18A1 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 U18A1 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 U18A1 Chevrolet Code

1. What are the common symptoms of OBDII code U18A1 on a Chevrolet related to lost communication with the coolant temperature control module?

The common symptoms may include engine overheating, inaccurate coolant temperature readings on the dashboard, and issues with the cooling system functionality.

2. What are the possible causes of the U18A1 OBDII code on a Chevrolet indicating lost communication with the coolant temperature control module?

Possible causes may include a faulty coolant temperature control module, damaged wiring or connectors in the CAN bus network, or a malfunctioning high voltage energy management system.

3. How can I diagnose the U18A1 code on my Chevrolet for lost communication with the coolant temperature control module?

Diagnosis involves checking the connections to the coolant temperature control module, inspecting the wiring for any damage, and using a diagnostic scanner to read the codes and monitor communication on the CAN bus network.

4. What are some repair tips for resolving the U18A1 code related to lost communication with the coolant temperature control module on a Chevrolet?

Repair tips may include repairing or replacing damaged wiring and connectors, resetting the codes with a diagnostic scanner, and ensuring proper communication between the control module and the CAN bus network.

5. Can driving with the U18A1 OBDII code on a Chevrolet lead to any serious issues?

Continued driving with this code may result in engine overheating, potential damage to the cooling system components, and inaccurate temperature readings that can affect engine performance.

6. Is it safe to clear the U18A1 code on a Chevrolet without addressing the underlying issue of lost communication with the coolant temperature control module?

Clearing the code without fixing the root cause may temporarily eliminate the warning light, but the issue will likely reoccur, leading to potential safety risks and ongoing problems with the cooling system.

7. How much does it typically cost to repair the U18A1 OBDII code on a Chevrolet involving lost communication with the coolant temperature control module?

The cost of repair can vary depending on the extent of the issue, but it may involve expenses for parts replacement, labor for diagnostics and repairs, and potential reprogramming of the control module.

8. Can a DIY enthusiast fix the U18A1 code related to lost communication with the coolant temperature control module on a Chevrolet?

While some DIY enthusiasts may have the skills to diagnose and repair basic wiring or connector issues, resolving complex problems with the coolant temperature control module and CAN bus network may require professional expertise.

9. Are there any preventive measures to avoid encountering the U18A1 OBDII code on a Chevrolet in the future?

Regular maintenance checks, timely inspections of the cooling system components, and addressing any warning signs promptly can help prevent issues leading to the U18A1 code and ensure proper functioning of the coolant temperature control module.

10. How urgent is it to address the U18A1 OBDII code indicating lost communication with the coolant temperature control module on a Chevrolet?

It is advisable to address the issue promptly to prevent potential damage to the engine, cooling system, and other related components. Ignoring the problem can lead to more severe issues and costly repairs in the future.