AutoCodes – Cadillac – P1338 Cadillac

P1338 Cadillac 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 Cadillac 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 484

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 Cadillac 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 Cadillac - Cylinder 1 Glow Plug Offset Exceeded Learning Limit - AutoCodes.com — P1338 Cadillac Code - Cylinder 1 Glow Plug Offset Exceeded Learning Limit

What does this mean?

What are the Possible Causes of the DTC P1338 Cadillac?

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 Cadillac?

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 Cadillac 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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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 Cadillac Code

What does the OBDII code P1338 mean for my Cadillac?

The P1338 code indicates that the Cylinder 1 glow plug offset has exceeded the learning limit, which can affect the engine's start-up and performance, especially in cold conditions.

What symptoms might I experience with code P1338?

Common symptoms include difficulty starting the engine, rough idling, decreased fuel efficiency, and increased exhaust emissions.

What could cause the P1338 code to trigger?

Possible causes include a faulty glow plug for Cylinder 1, issues with the glow plug control module, wiring problems, or a malfunctioning engine control unit (ECU).

Can I drive my Cadillac with the P1338 code?

While it may be possible to drive, it's not recommended as it can lead to poor engine performance and increased emissions. It's best to address the issue as soon as possible.

How can I diagnose the issue related to the P1338 code?

To diagnose the issue, check for any other codes, inspect the glow plug and its wiring for damage, test the glow plug with a multimeter, and verify the functionality of the glow plug control module.

What repairs are typically needed to fix the P1338 code?

Repairs may involve replacing the faulty glow plug, fixing any damaged wiring, or replacing the glow plug control module if it's found to be defective.

Will clearing the code P1338 fix the problem?

Clearing the code may temporarily turn off the check engine light, but if the underlying issue isn't fixed, the code will likely return.

Is it safe to replace the glow plug myself?

If you have experience with automotive repairs, you may be able to replace the glow plug yourself. However, if you're unsure or lack the necessary tools, it's best to seek professional help.

What should I do if the P1338 code reappears after repairs?

If the code reappears, it may indicate a deeper issue, such as an ECU malfunction or persistent wiring problems. In this case, further diagnostic testing is recommended.