P1338 2018 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 2018 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 2018 GMC Sierra Description
What are the Possible Causes of the DTC P1338 2018 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 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.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P1338 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.
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Frequently Asked Questions about P1338 2018 GMC Sierra Code
What does the OBDII code P1338 mean for a 2018 GMC Sierra?
P1338 indicates that the Cylinder 1 glow plug offset has exceeded the learning limit, suggesting an issue with the glow plug system or related components.
What are the common symptoms of code P1338 on a 2018 GMC Sierra?
Symptoms may include difficulty starting the engine, rough idling, reduced engine performance, or a check engine light.
What causes the P1338 code to appear on a 2018 GMC Sierra?
The code can be triggered by a faulty glow plug, wiring issues in the glow plug circuit, carbon buildup, or problems with the engine control module (ECM).
Can driving with the P1338 code damage the engine?
While the vehicle may still run, prolonged driving with this code can lead to further engine issues, especially in cold weather where glow plugs are critical for starting.
How is code P1338 diagnosed on a 2018 GMC Sierra?
A mechanic will typically use a scan tool to confirm the code, inspect the glow plug and wiring, and perform tests to determine if the offset error is due to a faulty component.
What parts might need to be replaced to fix the P1338 code?
Common replacements include the cylinder 1 glow plug, wiring harness, glow plug controller, or in rare cases, the engine control module.
Are there any DIY fixes for the P1338 code on a GMC Sierra?
Basic checks like inspecting the glow plug wiring for damage or corrosion can be done at home, but replacing components or recalibrating the ECM usually requires professional tools.
Can extreme weather affect the P1338 code on a 2018 GMC Sierra?
Yes, cold temperatures can exacerbate glow plug issues, leading to harder starts and a higher likelihood of the code appearing.
How much does it typically cost to repair the P1338 code?
Repair costs can vary, but replacing a glow plug may cost $100-$300, while more extensive repairs like wiring replacement or ECM reprogramming can exceed $500.
How can I prevent the P1338 code from recurring?
Regular maintenance, including checking glow plugs for wear and ensuring clean and secure wiring connections, can help prevent this code from reappearing.
Discuss the causes and fixes for P1338 2018 GMC Sierra OBDII Code
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