P1338 2015 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 2015 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.
Code P1338 2015 GMC Sierra Description
What are the Possible Causes of the DTC P1338 2015 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 2015 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.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P1338 2015 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.
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Frequently Asked Questions about P1338 2015 GMC Sierra Code
What does OBDII code P1338 mean for a 2015 GMC Sierra?
Code P1338 indicates that the glow plug offset for cylinder 1 has exceeded the learning limit set by the engine control module (ECM).
What are the common symptoms of code P1338 in a 2015 GMC Sierra?
Symptoms may include difficulty starting the engine, rough idling, reduced fuel efficiency, and potentially a check engine light.
What causes code P1338 to appear in a 2015 GMC Sierra?
Common causes include a faulty glow plug for cylinder 1, wiring issues, poor electrical connections, or a malfunctioning ECM.
Can a bad glow plug cause code P1338 in a 2015 GMC Sierra?
Yes, a defective glow plug in cylinder 1 can trigger this code because it affects the ECM’s ability to calibrate the offset.
How can I diagnose code P1338 on a 2015 GMC Sierra?
Start by inspecting the glow plug in cylinder 1, checking the wiring and connectors for damage, and using an OBDII scanner to confirm the code.
Is it safe to drive with code P1338 on a 2015 GMC Sierra?
While the vehicle may still drive, prolonged operation with this code can lead to increased emissions and engine starting issues. It’s best to address it promptly.
How do I fix code P1338 on a 2015 GMC Sierra?
Repairs often involve replacing the cylinder 1 glow plug, fixing damaged wiring or connectors, or reprogramming the ECM if necessary.
What tools are needed to fix code P1338 on a 2015 GMC Sierra?
You’ll need an OBDII scanner, a multimeter for electrical checks, basic hand tools, and possibly a replacement glow plug.
Can a software update fix code P1338 on a 2015 GMC Sierra?
Yes, if the code is caused by an ECM calibration issue, updating or reprogramming the ECM may resolve it.
How much does it cost to repair code P1338 on a 2015 GMC Sierra?
Repair costs vary but typically range from $50 to $200 for a glow plug replacement, plus labor if done by a mechanic.
Discuss the causes and fixes for P1338 2015 GMC Sierra OBDII Code
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