AutoCodes – GMC – P1338 2014 GMC Sierra

P1338 2014 GMC Sierra Code - Cylinder 1 Glow Plug Offset Exceeded Learning Limit

Quick Answer

The Glow Plug Control Module has not learned the glow plug offset values. Common causes include Perform Glow Plug Learn procedure, Faulty Glow Plug 1, Glow Plug 1 harness is open or shorted. 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: P1338 2014 GMC Sierra indicates Cylinder 1 Glow Plug Offset Exceeded Learning Limit.
Common causes: Common causes include Perform Glow Plug Learn procedure, Faulty Glow Plug 1, Glow Plug 1 harness is open or shorted.
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 307

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 Sep 30, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P1338 2014 GMC Sierra Description

The Glow Plug Control Module has not learned the glow plug offset values. If a glow plug has been replaced and the glow plug learn was not performed, or if the Glow Plug Control Module experiences an Electronically Erasable Programmable Read Only Memory (EEPROM) error or data corruption, this Diagnostic Trouble Code (DTC) to set. The DTC will be set if the glow plug hot resistance is outside a predefined threshold.

OBDII Code P1338 2014 GMC Sierra - Cylinder 1 Glow Plug Offset Exceeded Learning Limit - AutoCodes.com — P1338 2014 GMC Sierra Code - Cylinder 1 Glow Plug Offset Exceeded Learning Limit

What does this mean?

What are the Possible Causes of the DTC P1338 2014 GMC Sierra?

Perform Glow Plug Learn procedure
Faulty Glow Plug 1
Glow Plug 1 harness is open or shorted
Glow Plug 1 circuit poor electrical connection

How to Fix the DTC P1338 2014 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 does this mean?

Code Tech Notes

If a Glow Plug was replaced, perform a Glow Plug Learn procedure with a Scan Tool.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1338 2014 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 P1338 2014 GMC Sierra code?

Need more information on how to fix the P1338 2014 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1338 2014 GMC Sierra 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 P1338 2014 GMC Sierra Code

1. What does the OBDII code P1338 mean on a 2014 GMC Sierra?

P1338 indicates that the Cylinder 1 Glow Plug Offset has exceeded the learning limit, meaning the engine control module (ECM) has detected an issue with the glow plug's performance in cylinder 1.

2. What are the common symptoms of code P1338 on a 2014 GMC Sierra?

Common symptoms include difficulty starting in cold weather, rough idling, reduced engine performance, and the illumination of the check engine light.

3. What causes the P1338 code to appear on a 2014 GMC Sierra?

Potential causes include a faulty glow plug in cylinder 1, poor electrical connections, damaged wiring, or an issue with the glow plug control module.

4. How do I diagnose the P1338 code on my 2014 GMC Sierra?

Start by inspecting the glow plug in cylinder 1, checking for damage or wear. Then, test the electrical connections and wiring for continuity and ensure the glow plug control module is functioning properly.

5. Can I drive my 2014 GMC Sierra with the P1338 code?

While the truck may still run, driving with the P1338 code is not recommended as it could lead to starting issues, poor performance, and potential damage to other engine components over time.

6. How do I fix the P1338 code on a 2014 GMC Sierra?

Repairs may involve replacing the faulty glow plug in cylinder 1, repairing damaged wiring or connections, or replacing the glow plug control module if necessary.

7. How much does it cost to fix the P1338 code on a 2014 GMC Sierra?

The repair cost can vary but typically ranges from $100 to $300 depending on whether the glow plug or control module needs replacing and labor costs in your area.

8. Can a bad glow plug cause other issues in my 2014 GMC Sierra?

Yes, a bad glow plug can cause poor fuel combustion, reduced fuel efficiency, and increased emissions, as well as potential difficulty starting the engine in cold conditions.

9. Do I need to clear the P1338 code after repairs?

Yes, after completing repairs, clear the code with an OBDII scanner and perform a drive cycle to ensure the issue has been resolved and the code does not return.

10. How can I prevent the P1338 code from occurring again on my 2014 GMC Sierra?

Regularly inspect and maintain the glow plugs, wiring, and control module, especially before cold weather, to prevent issues that could trigger the P1338 code.