AutoCodes – Generic – U3018

U3018 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 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 3,585

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

What does this mean?

What are the Possible Causes of the DTC U3018?

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?

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 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 U3018 code?

Need more information on how to fix the U3018 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U3018 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U3018 Buick — Control Module Supply Circuit 1-2 Not Plausible
U3018 Cadillac — Control Module Supply Circuit 1-2 Not Plausible
U3018 Chevrolet — Control Module Supply Circuit 1-2 Not Plausible
U3018 GMC — Control Module Supply Circuit 1-2 Not Plausible

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 Code

1. What are the common symptoms of OBDII code U3018 (Control Module Supply Circuit 1-2 Not Plausible)?

- Common symptoms include rough idling, poor engine performance, stalling, and illuminated Check Engine Light.

2. What are the potential causes of OBDII code U3018?

- Possible causes may include a faulty control module, wiring issues, a damaged connector, or a problem with the power supply circuit.

3. How can I diagnose OBDII code U3018?

- Diagnosis typically involves using a diagnostic scanner to retrieve the trouble codes, checking the power supply to the control module, inspecting the wiring and connectors, and performing component tests.

4. Can a DIYer repair OBDII code U3018 at home?

- While basic troubleshooting like checking connections and fuses can be done at home, repairing this code may require professional knowledge and specialized tools due to the complexity of the control module and wiring systems.

5. Is it safe to continue driving with OBDII code U3018 present?

- It is not recommended to drive with this code active, as it may lead to further vehicle performance issues and potential safety concerns. It's advisable to address the problem promptly.

6. How much does it typically cost to repair OBDII code U3018?

- Repair costs can vary depending on the specific cause of the issue, but expect expenses for parts and labor. Costs may range from a few hundred to over a thousand dollars, depending on the extent of the repairs needed.

7. Can a weak car battery cause OBDII code U3018 to trigger?

- A weak car battery can potentially cause voltage irregularities that may trigger this code. It's advisable to ensure the battery is in good condition before diagnosing further.

8. Will resetting the trouble codes make OBDII code U3018 disappear permanently?

- Simply resetting the trouble codes may temporarily clear the Check Engine Light, but if the underlying issue causing U3018 is not addressed, the code is likely to reappear after a short period.

9. Are there any recalls related to OBDII code U3018 in certain vehicle models?

- Recalls related to this specific OBDII code can vary by vehicle manufacturer. It's recommended to check with the manufacturer or a dealership to see if any recalls apply to your vehicle.

10. Can OBDII code U3018 be caused by water damage to the control module?

- Yes, water damage to the control module or its connections can potentially trigger this code. It's important to inspect for any signs of water intrusion during diagnosis.