AutoCodes – GMC – U18C8 2017 GMC Sierra

U18C8 2017 GMC Sierra Code - Glow Plug Control Module Lost Communication with Engine Control Module

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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: U18C8 2017 GMC Sierra indicates Glow Plug Control Module Lost Communication with Engine Control Module.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 235

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 Jul 24, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code U18C8 2017 GMC Sierra 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 be set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U18C8 2017 GMC Sierra - Glow Plug Control Module Lost Communication with Engine Control Module - AutoCodes.com — U18C8 2017 GMC Sierra Code - Glow Plug Control Module Lost Communication with Engine Control Module

What does this mean?

What are the Possible Causes of the DTC U18C8 2017 GMC Sierra?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC U18C8 2017 GMC Sierra?

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 U18C8 2017 GMC Sierra 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 U18C8 2017 GMC Sierra code?

Need more information on how to fix the U18C8 2017 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U18C8 2017 GMC Sierra 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 U18C8 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code U18C8 in a 2017 GMC Sierra?

The common symptoms may include hard starting, rough idling, reduced engine performance, and the illumination of the Check Engine Light.

2. What does the OBDII code U18C8 "Glow Plug Control Module Lost Communication with Engine Control Module" mean for a 2017 GMC Sierra?

This code indicates a communication issue between the glow plug control module and the engine control module, potentially affecting the glow plug system's operation.

3. What are the possible causes of code U18C8 in a 2017 GMC Sierra?

The code U18C8 can be triggered by issues such as damaged wiring, faulty control modules, poor electrical connections, or software malfunctions.

4. How can I diagnose OBDII code U18C8 in my 2017 GMC Sierra?

To diagnose code U18C8, it is recommended to perform a thorough inspection of the wiring, connectors, and control modules related to the glow plug system. Additionally, using a diagnostic scanner to check for communication errors can help pinpoint the issue.

5. What are the repair options for OBDII code U18C8 in a 2017 GMC Sierra?

Repair options include repairing or replacing damaged wiring, addressing faulty control modules, ensuring proper electrical connections, and updating software as needed.

6. Can I continue driving my 2017 GMC Sierra with code U18C8?

It is generally not recommended to drive your vehicle with unresolved OBDII codes, as they can lead to further issues and potential damage. It's best to address the problem promptly.

7. How much does it cost to repair OBDII code U18C8 in a 2017 GMC Sierra?

The cost of repairing code U18C8 can vary depending on the specific cause of the issue, the needed parts, labor costs, and whether the repairs are done at a dealership or an independent mechanic.

8. Are there any preventive measures to avoid OBDII code U18C8 in a 2017 GMC Sierra?

Regular maintenance, such as checking the glow plug system components during scheduled services, can help prevent issues that may trigger code U18C8.

9. Can a DIY enthusiast fix OBDII code U18C8 in a 2017 GMC Sierra?

Depending on the individual's skill level and access to tools, some DIY enthusiasts may be able to diagnose and repair simpler causes of code U18C8, such as checking and cleaning electrical connections.

10. Is OBDII code U18C8 a common issue in 2017 GMC Sierra vehicles?

While the frequency of encountering this specific code may vary, communication issues between modules are not uncommon in modern vehicles and can occur in 2017 GMC Sierra models as well.