AutoCodes – GMC – P1223 GMC

P1223 GMC Code - Injector 1 Output Circuit

Quick Answer

The Engine Control Module (ECM) enables the appropriate fuel injector on the compression stroke for each cylinder. Common causes include Faulty Fuel Injector 1, Fuel Injector 1 harness is open or shorted, Fuel Injector 1 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: P1223 GMC indicates Injector 1 Output Circuit.
Common causes: Common causes include Faulty Fuel Injector 1, Fuel Injector 1 harness is open or shorted, Fuel Injector 1 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 2,337

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 25, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P1223 GMC Description

The Engine Control Module (ECM) enables the appropriate fuel injector on the compression stroke for each cylinder. The ECM controls the Fuel Injection Control Module (FICM) by grounding the control circuit via a solid state device called a driver. The ECM monitors the state of the driver. If the ECM detects an incorrect voltage for the commanded state of an injector driver, Diagnostic Trouble Code (DTC) P1223, P1226, P1229, P1232, P1235, P1238, P1241, or P1244 will set.

OBDII Code P1223 GMC - Injector 1 Output Circuit - AutoCodes.com — P1223 GMC Code - Injector 1 Output Circuit

What does this mean?

What are the Possible Causes of the DTC P1223 GMC?

Faulty Fuel Injector 1
Fuel Injector 1 harness is open or shorted
Fuel Injector 1 circuit poor electrical connection
Faulty Fuel Injection Control Module (FICM)
Faulty Engine Control Module (ECM)

How to Fix the DTC P1223 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 does this mean?

Code Tech Notes

If only 1 fuel injector Control circuit Diagnostic Trouble Code (DTC) is set, an open circuit or poor connection is the most likely cause. If groups of 4 fuel injector Control circuit DTCs are set, suspect a short to ground. Cylinder groups are 2, 3, 5, 8 or 1, 4, 6, 7. More than 4 fuel injector Control circuit DTCs set indicate short to voltage on fuel injector Control circuit is the most likely cause.

There is a factory service bulletin for the following models:

2004 GMC Sierra
2005 GMC Sierra
2004 GMC Topkick
2005 GMC Topkick
2004-2005 GMC Sierra, Topkick Factory Service Bulletin OBDII Code P1223

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1223 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.

Need more information about the P1223 GMC code?

Need more information on how to fix the P1223 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1223 GMC 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 P1223 GMC Code

1. What are the common symptoms of OBDII code P1223 GMC (Injector 1 Output Circuit)?

Symptoms may include engine misfires, rough idling, poor acceleration, and decreased fuel efficiency.

2. What are the possible causes of OBDII code P1223 GMC?

Potential causes include a faulty fuel injector, wiring issues in the injector circuit, poor electrical connection, or an ECM (Engine Control Module) malfunction.

3. How can I diagnose the Injector 1 Output Circuit issue?

Diagnosis typically involves using a scan tool to read the code, testing the injector and its wiring for continuity and resistance, and inspecting for any visible damage.

4. Can a DIYer repair OBDII code P1223 GMC?

If you have experience with automotive electrical systems and the necessary tools, you may be able to repair this issue yourself. However, seeking professional help is recommended if you're unsure.

5. What are some repair tips for addressing OBDII code P1223 GMC?

Ensure the fuel injector is receiving power and ground, check for damaged wiring or loose connections, and consider testing the ECM to rule out any potential malfunctions.

6. Will driving with OBDII code P1223 GMC cause further damage to my vehicle?

Continuing to drive with this code may lead to poor engine performance and reduced fuel efficiency. It's best to address the issue promptly to prevent any potential long-term damage.

7. How much does it cost to repair OBDII code P1223 GMC?

The cost of repairs can vary depending on the root cause of the issue, the labor rates in your area, and whether you choose to repair it yourself or seek professional assistance.

8. Can a faulty fuel injector be the sole cause of OBDII code P1223 GMC?

While a faulty fuel injector is a common cause of this code, it's essential to thoroughly diagnose the issue to rule out other potential causes like wiring problems or ECM issues.

9. How long does it typically take to repair OBDII code P1223 GMC?

The repair time can vary based on the complexity of the issue and your level of expertise. It could take anywhere from a few hours to a day to address the problem effectively.

10. Is it safe to drive my vehicle with the OBDII code P1223 GMC (Injector 1 Output Circuit) unresolved?

It's generally not recommended to drive with this code unresolved, as it can lead to performance issues and potentially cause further damage to your vehicle.