AutoCodes – GMC – P124A 2018 GMC Sierra

P124A 2018 GMC Sierra Code - Injector 3 Positive Voltage Control Circuit Shorted to Control Circuit

Quick Answer

The Engine Control Module (ECM) supplies voltage to each fuel injector on the injector high voltage supply circuits. Common causes include Faulty Fuel Injector 3, Fuel Injector 3 harness is open or shorted, Fuel Injector 3 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: P124A 2018 GMC Sierra indicates Injector 3 Positive Voltage Control Circuit Shorted to Control Circuit.
Common causes: Common causes include Faulty Fuel Injector 3, Fuel Injector 3 harness is open or shorted, Fuel Injector 3 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 234

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Aug 12, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P124A 2018 GMC Sierra Description

The Engine Control Module (ECM) supplies voltage to each fuel injector on the injector high voltage supply circuits. The ECM energizes each fuel injector by grounding the high voltage control circuit of the fuel injector. The ECM monitors the status of the injector high voltage supply circuits and the fuel injector high voltage control circuits. When a fuel injector circuit condition is detected by the ECM, the affected fuel injector(s) is disabled. The Diagnostic Trouble Code (DTC) will be set if the ECM detects the injector high control circuit is shorted to the low control circuit for greater than 2 s.

OBDII Code P124A 2018 GMC Sierra - Injector 3 Positive Voltage Control Circuit Shorted to Control Circuit - AutoCodes.com — P124A 2018 GMC Sierra Code - Injector 3 Positive Voltage Control Circuit Shorted to Control Circuit

What does this mean?

What are the Possible Causes of the DTC P124A 2018 GMC Sierra?

Faulty Fuel Injector 3
Fuel Injector 3 harness is open or shorted
Fuel Injector 3 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P124A 2018 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 P124A 2018 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 P124A 2018 GMC Sierra code?

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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 P124A 2018 GMC Sierra Code

1. What does the OBDII code P124A mean on a 2018 GMC Sierra?

P124A indicates a problem with Injector 3â€™s positive voltage control circuit, specifically a short between the positive control circuit and the control circuit.

2. What are the common symptoms of code P124A in a 2018 GMC Sierra?

Symptoms may include rough idle, engine misfires, reduced power, poor fuel efficiency, and an illuminated check engine light.

3. What causes the P124A code to appear on a 2018 GMC Sierra?

The code can be caused by damaged or corroded wiring, a short circuit, a faulty fuel injector, a bad engine control module (ECM), or loose electrical connections.

4. Can a bad fuel injector cause the P124A code?

Yes, a faulty or failing fuel injector for cylinder 3 can cause this code by creating electrical issues in its control circuit.

5. How do I diagnose the P124A code on my 2018 GMC Sierra?

Start by inspecting the wiring and connectors for Injector 3 for damage or corrosion. Use a multimeter to check for continuity and shorts in the circuit, and test the injector itself for proper operation.

6. Is it safe to drive my 2018 GMC Sierra with the P124A code?

Itâ€™s not recommended to drive with this code, as it may lead to further engine damage or unsafe driving conditions due to misfires or reduced power.

7. How do I fix the P124A code on a 2018 GMC Sierra?

Repairs may include replacing damaged wiring or connectors, repairing short circuits, replacing Injector 3, or reprogramming or replacing the ECM if necessary.

8. How much does it cost to fix the P124A code on a 2018 GMC Sierra?

Repair costs vary but may range from $100 to $300 for wiring repairs or up to $500+ if the injector or ECM needs replacement.

9. Can a dirty connector cause the P124A code?

Yes, a corroded or dirty connector can create poor electrical contact, potentially causing the circuit to short and trigger this code.

10. Does clearing the P124A code with a scan tool fix the problem?

Clearing the code will reset the check engine light, but it wonâ€™t fix the underlying issue. The problem must be diagnosed and repaired to prevent the code from returning.