AutoCodes – GMC – U3018 GMC

U3018 GMC Code - Control Module Supply Circuit 1-2 Not Plausible

Quick Answer

The vehicle control modules or sensors monitor the system voltage to verify the system voltage is within the normal operating range. Common causes include Faulty Control Module setting the code, Control Module harness is open or shorted, 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: U3018 GMC indicates Control Module Supply Circuit 1-2 Not Plausible.
Common causes: Common causes include Faulty Control Module setting the code, Control Module harness is open or shorted, 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 692

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 18, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U3018 GMC Description

The vehicle control modules or sensors monitor the system voltage to verify the system voltage is within the normal operating range. With the ignition is ON, the Diagnostic Trouble Code (DTC) will set when the control module or sensor detects a system voltage of less than approximately 9 V for approximately 5 s.

OBDII Code U3018 GMC - Control Module Supply Circuit 1-2 Not Plausible - AutoCodes.com — U3018 GMC Code - Control Module Supply Circuit 1-2 Not Plausible

What does this mean?

What are the Possible Causes of the DTC U3018 GMC?

Faulty Control Module setting the code
Control Module harness is open or shorted
Control Module circuit poor electrical connection

How to Fix the DTC U3018 GMC?

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 U3018 GMC 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 U3018 GMC Code

1. What are the common symptoms of OBDII code U3018 GMC?

The common symptoms of code U3018 GMC include issues with engine performance, rough idling, stalling, and the illumination of the Check Engine Light.

2. What does the OBDII code U3018 GMC indicate?

Code U3018 GMC indicates that the control module supply circuit 1-2 is not plausible, meaning there is a discrepancy between the expected voltage levels in the circuit.

3. What are the possible causes of OBDII code U3018 GMC?

Possible causes of code U3018 GMC include a faulty control module, damaged wiring or connectors in the supply circuit, a weak battery, or a malfunctioning power relay.

4. How can I diagnose OBDII code U3018 GMC?

Diagnosing code U3018 GMC involves using a scan tool to retrieve the code and checking the control module supply circuit for any issues such as loose connections, damaged wiring, or faulty components.

5. Can I still drive my vehicle with OBDII code U3018 GMC?

It is not recommended to drive your vehicle with an active U3018 GMC code, as it can lead to further damage or safety hazards. It is best to address the issue promptly.

6. How do I repair OBDII code U3018 GMC?

To repair code U3018 GMC, you may need to replace a faulty control module, repair damaged wiring or connectors, check and replace the power relay if necessary, and clear the code from the vehicle's computer.

7. Will resetting the OBDII code U3018 GMC make it go away permanently?

Resetting the code may temporarily turn off the Check Engine Light, but if the underlying issue causing the code is not addressed, it is likely to return. It's essential to diagnose and repair the problem to prevent further issues.

8. Is OBDII code U3018 GMC a serious problem?

Code U3018 GMC should be addressed promptly to prevent potential drivability issues and further damage to the vehicle. Ignoring the code could lead to more severe problems over time.

9. Can a DIY enthusiast fix OBDII code U3018 GMC?

Depending on your skill level and access to tools, a DIY enthusiast may be able to diagnose and repair code U3018 GMC. However, it is recommended to consult a professional mechanic for a comprehensive diagnosis and repair.

10. How much does it cost to fix OBDII code U3018 GMC?

The cost to fix code U3018 GMC can vary depending on the root cause of the issue, the parts needed for repair, and the labor rates of the repair shop. It is advisable to get a few quotes from different mechanics to compare prices.