AutoCodes – GMC – P2156 2018 GMC Sierra

P2156 2018 GMC Sierra Code - Cylinder 4 Injector High Control Circuit Low Voltage

Quick Answer

The Engine Control Module (ECM) supplies voltage to each fuel injector on the high control circuits. Common causes include Faulty Fuel Injector 4, Fuel Injector 4 harness is open or shorted, Fuel Injector 4 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: P2156 2018 GMC Sierra indicates Cylinder 4 Injector High Control Circuit Low Voltage.
Common causes: Common causes include Faulty Fuel Injector 4, Fuel Injector 4 harness is open or shorted, Fuel Injector 4 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 305

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 Sep 08, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2156 2018 GMC Sierra Description

The Engine Control Module (ECM) supplies voltage to each fuel injector on the high control circuits. The ECM energizes each fuel injector by grounding the low control circuit of the fuel injector. The ECM monitors the status of the fuel injector 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 when the ECM detects the fuel injector high voltage supply circuit is shorted to ground for greater than 2 s.

OBDII Code P2156 2018 GMC Sierra - Cylinder 4 Injector High Control Circuit Low Voltage - AutoCodes.com — P2156 2018 GMC Sierra Code - Cylinder 4 Injector High Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P2156 2018 GMC Sierra?

Faulty Fuel Injector 4
Fuel Injector 4 harness is open or shorted
Fuel Injector 4 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P2156 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 P2156 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 P2156 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 P2156 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P2156 in a 2018 GMC Sierra?

- Common symptoms include rough idling, engine misfires, decreased fuel efficiency, and potentially a check engine light.

2. What does the OBDII code P2156 "Cylinder 4 Injector High Control Circuit Low Voltage" mean for a 2018 GMC Sierra?

- This code indicates an issue with the control circuit of the fuel injector for cylinder 4, specifically relating to low voltage.

3. What are the possible causes of the OBDII code P2156 in a 2018 GMC Sierra?

- Potential causes include a faulty fuel injector for cylinder 4, wiring issues in the injector circuit, poor electrical connections, or a problem with the Engine Control Module (ECM).

4. How can I diagnose the OBDII code P2156 in my 2018 GMC Sierra?

- Diagnosing this code typically involves checking the wiring and connections related to the fuel injector for cylinder 4, testing the injector itself, and inspecting the ECM for any faults.

5. Can I continue driving my 2018 GMC Sierra with OBDII code P2156?

- It is not recommended to continue driving with this code present, as it can lead to engine performance issues and potentially cause further damage if left unresolved.

6. How should I repair OBDII code P2156 in my 2018 GMC Sierra?

- Repairing this code may involve replacing the fuel injector for cylinder 4, repairing any damaged wiring or connections, and resetting the ECM after addressing the issue.

7. Is it possible to clear the OBDII code P2156 in a 2018 GMC Sierra without fixing the underlying problem?

- While you can clear the code temporarily, it will likely reappear if the root cause of the issue is not addressed, potentially leading to ongoing performance issues.

8. Are there any preventive maintenance tips to avoid OBDII code P2156 in a 2018 GMC Sierra?

- Regularly servicing the fuel injection system, checking and maintaining electrical connections, and ensuring proper engine performance can help prevent issues that trigger this code.

9. How much does it typically cost to fix OBDII code P2156 in a 2018 GMC Sierra?

- The cost of fixing this code can vary depending on the specific cause of the issue, but it may involve parts and labor ranging from a few hundred to a thousand dollars.

10. Can I fix OBDII code P2156 in a 2018 GMC Sierra myself, or should I seek professional help?

- While some DIY enthusiasts may be able to address this issue, it is often recommended to seek professional help, especially if you are not experienced with diagnosing and repairing engine-related problems.