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

Quick Answer

The P0603 diagnostic trouble code (DTC) in a 2015 GMC Sierra indicates that the Engine Control Module (ECM) has detected a loss of long-term memory. Common causes include Faulty ECM, Poor electrical connection to the ECM, Software glitch in the ECM. 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 Faulty ECM, Poor electrical connection to the ECM, Software glitch in the ECM.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 14, 2024
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Code P0603 2015 GMC Sierra Description

The P0603 diagnostic trouble code (DTC) in a 2015 GMC Sierra indicates that the Engine Control Module (ECM) has detected a loss of long-term memory. The ECM is responsible for controlling various engine functions, such as fuel injection, ignition timing, and emissions systems. Long-term memory refers to the stored data that the ECM uses to make adjustments and optimize engine performance over time.

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

Common Causes of P0603 2015 GMC Sierra

  1. Faulty ECM
  2. Poor electrical connection to the ECM
  3. Software glitch in the ECM
  4. Voltage spikes or electrical interference
  5. Extreme temperature changes

Symptoms of P0603 2015 GMC Sierra

  1. Rough engine idle
  2. Poor fuel economy
  3. Hesitation or stalling
  4. Failure to start
  5. Increased emissions

How to Fix P0603 2015 GMC Sierra

  1. Use a diagnostic scanner to retrieve the trouble codes and data from the ECM.
  2. Inspect the electrical connections to the ECM for corrosion or damage.
  3. Check for any software updates or reprogramming available for the ECM.
  4. If necessary, replace the ECM with a new or remanufactured unit.
  5. Clear the trouble codes and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0603 2015 GMC Sierra

The cost to repair a P0603 code in a 2015 GMC Sierra can vary depending on the specific cause of the issue. In general, replacing the ECM can cost anywhere from $500 to $1000, including parts and labor. However, the total cost may be higher if additional diagnostics or repairs are needed. It's recommended to consult with a qualified mechanic or dealership to get an accurate estimate based on the specific circumstances of your vehicle. Keep in mind that labor rates can vary between different shops and locations.

What does this mean?

Tech Notes for P0603 2015 GMC Sierra

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).

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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.

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