AutoCodes – GMC – P0603 2015 GMC Sierra

P0603 2015 GMC Sierra Code - Control Module Long Term Memory Reset

Quick Answer

This diagnostic applies to internal microprocessor integrity conditions within the Engine Control Module (ECM). Common causes include Low battery voltage, Reprogram Engine Control Module (ECM), Faulty Engine Control Module. 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: P0603 2015 GMC Sierra indicates Control Module Long Term Memory Reset.
Common causes: Common causes include Low battery voltage, Reprogram Engine Control Module (ECM), Faulty Engine Control Module.
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 186

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 29, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0603 2015 GMC Sierra Description

This diagnostic applies to internal microprocessor integrity conditions within the Engine Control Module (ECM). This diagnostic also addresses if the ECM is not programmed. The ECM monitors its ability to read and write to the memory. It also monitors a timing function. No external circuits are involved. The Diagnostic Trouble Code (DTC) will be set when the ECM detects an internal failure or incomplete programming for more than 10 s.

OBDII Code P0603 2015 GMC Sierra - Control Module Long Term Memory Reset - AutoCodes.com — P0603 2015 GMC Sierra Code - Control Module Long Term Memory Reset

What does this mean?

What are the Possible Causes of the DTC P0603 2015 GMC Sierra?

Low battery voltage
Reprogram Engine Control Module (ECM)
Faulty Engine Control Module
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC P0603 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.

What does this mean?

Code Tech Notes

Start by charging the vehicle's battery and clean terminal, once the battery is charged and the terminals are clean and secured, erase the code. If the code comes back ON, then you may have to reprogram or replace Powertrain Control Module (PCM).

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0603 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.

Need more information about the P0603 2015 GMC Sierra code?

Need more information on how to fix the P0603 2015 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 P0603 2015 GMC Sierra Code

1. What does the OBDII code P0603 mean on a 2015 GMC Sierra?

P0603 indicates an issue with the Control Module Long Term Memory Reset, meaning the ECM/PCM has lost stored information, such as learned parameters or adaptive settings.

2. What are the common symptoms of the P0603 code on a 2015 GMC Sierra?

Symptoms may include a check engine light, erratic engine performance, poor fuel economy, difficulty starting, or loss of adaptive transmission settings.

3. What causes the P0603 code on a 2015 GMC Sierra?

Common causes include a weak or disconnected battery, faulty or loose battery cables, ECM/PCM programming issues, or electrical interference from aftermarket accessories.

4. Is the P0603 code serious on a 2015 GMC Sierra?

While it may not immediately affect drivability, the code should be addressed promptly, as it can lead to inconsistent engine or transmission performance over time.

5. Can a weak battery trigger the P0603 code on a 2015 GMC Sierra?

Yes, a weak or failing battery can cause voltage drops, which may result in the ECM/PCM losing long-term memory and setting the P0603 code.

6. How can I fix the P0603 code on my 2015 GMC Sierra?

Start by checking the battery and cables for proper voltage and secure connections. If the issue persists, inspect the ECM/PCM for firmware updates or potential hardware faults.

7. Will clearing the P0603 code fix the issue permanently?

Clearing the code may temporarily turn off the check engine light, but the underlying issue must be resolved to prevent the code from returning.

8. Can aftermarket modifications cause the P0603 code on a 2015 GMC Sierra?

Yes, certain aftermarket tuners, accessories, or improper modifications can interfere with the ECM/PCM and trigger the P0603 code.

9. Do I need to replace the ECM/PCM to resolve the P0603 code on a 2015 GMC Sierra?

Replacement is usually a last resort. First, check for simpler issues like battery connections and consider reprogramming or updating the ECM/PCM firmware.

10. Can I still drive my 2015 GMC Sierra with a P0603 code?

In most cases, the vehicle is drivable, but you may experience reduced performance or efficiency. It is best to diagnose and repair the issue as soon as possible.