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Engine-Codes – GMC – P0603 GMC

P0603 GMC Code - Control Module Long Term Memory Reset

Quick Answer

When a GMC vehicle displays the diagnostic trouble code P0603, it indicates that the engine control module (ECM) has detected a long-term memory reset error. Common causes include Weak or failing battery causing voltage fluctuations, Faulty ECM power supply or wiring, Corrosion or poor connections in the ECM terminals. 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 GMC indicates Control Module Long Term Memory Reset.
Common causes
Common causes include Weak or failing battery causing voltage fluctuations, Faulty ECM power supply or wiring, Corrosion or poor connections in the ECM terminals.
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 08, 2024
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Code P0603 GMC Description

When a GMC vehicle displays the diagnostic trouble code P0603, it indicates that the engine control module (ECM) has detected a long-term memory reset error. The ECM is a crucial component of the vehicle's onboard computer system, responsible for monitoring and controlling various engine functions, including fuel injection, ignition timing, and emission control systems.

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

Common Causes of P0603 GMC

  1. Weak or failing battery causing voltage fluctuations
  2. Faulty ECM power supply or wiring
  3. Corrosion or poor connections in the ECM terminals
  4. Software issues or programming errors in the ECM
  5. Extreme temperature fluctuations affecting the ECM

Symptoms of P0603 GMC

  1. Check engine light illuminated on the dashboard
  2. Engine running rough or misfiring
  3. Decreased fuel efficiency
  4. Difficulty starting the vehicle
  5. Loss of power while driving

How to Fix P0603 GMC

  1. Begin by diagnosing the specific cause of the long-term memory reset error using a diagnostic scanner to retrieve freeze frame data and pinpoint the issue.
  2. Check the battery voltage and connections to ensure they are in good condition. Replace the battery if necessary.
  3. Inspect the ECM power supply and wiring for any signs of damage or corrosion. Repair or replace as needed.
  4. Clean the ECM terminals and ensure secure connections are established to prevent future disruptions in power supply.
  5. Update the ECM software or reprogram it if software issues are identified as the cause of the error code.

Cost to Fix P0603 GMC

The cost of repairing a P0603 code on a GMC vehicle can vary depending on the specific cause of the issue and the labor rates in your area. On average, the repair costs for this type of issue can range from $200 to $500, including parts and labor. Keep in mind that diagnostic time and labor rates at auto repair shops can fluctuate, so it's recommended to obtain a detailed estimate from a professional technician before proceeding with the repair.

What does this mean?

Tech Notes for P0603 GMC

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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Information for Specific GMC Models

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 GMC Code

1. What are the common symptoms of OBDII code P0603 in a GMC vehicle?

- The common symptoms of OBDII code P0603 include engine stalling, rough idling, poor fuel efficiency, and possibly issues with starting the vehicle.

2. What does the OBDII code P0603 "Control Module Long Term Memory Reset" mean in a GMC vehicle?

- The code P0603 indicates that the Engine Control Module (ECM) has detected a loss of long-term memory or that the memory has been reset.

3. What are the possible causes of OBDII code P0603 in a GMC vehicle?

- The possible causes of code P0603 include a faulty ECM, a dead or disconnected battery, poor electrical connections, or even issues with the vehicle's software.

4. How can I diagnose OBDII code P0603 in my GMC vehicle?

- Diagnosing code P0603 typically involves checking the electrical connections to the ECM, inspecting the battery for proper voltage, and using a diagnostic scanner to reset the ECM and monitor its behavior.

5. Can I continue driving my GMC vehicle with OBDII code P0603 present?

- It is not recommended to drive your GMC vehicle with code P0603 present, as it can lead to more serious issues with the engine's performance and overall drivability.

6. How can I repair OBDII code P0603 in my GMC vehicle?

- Repairing code P0603 may involve resetting the ECM, checking and repairing any faulty electrical connections, ensuring the battery is in good condition, or replacing the ECM if necessary.

7. Is it possible to reset OBDII code P0603 in a GMC vehicle without professional help?

- While some simple troubleshooting steps can be taken, it is recommended to seek professional help to properly diagnose and repair OBDII code P0603 in a GMC vehicle.

8. Will disconnecting the battery reset OBDII code P0603 in a GMC vehicle?

- Disconnecting the battery may temporarily clear the code, but it is not a permanent solution. It is important to diagnose and address the underlying issue to prevent the code from reappearing.

9. How long does it take to repair OBDII code P0603 in a GMC vehicle?

- The time it takes to repair code P0603 can vary depending on the cause of the issue. Simple fixes like resetting the ECM or checking electrical connections may take less time, while more complex repairs could require more extensive work.

10. Can OBDII code P0603 in a GMC vehicle be triggered by a one-time issue?

- Yes, code P0603 can sometimes be triggered by a one-time issue such as a momentary loss of power. However, if the code reoccurs, it indicates a persistent problem that needs to be addressed.

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