How to Fix P0602: Control Module Read Only Memory (ROM)

Control Module Read Only Memory (ROM) plays a crucial role in the proper functioning of vehicle control modules.

When a P0602 error code appears, it indicates a problem with the ROM, which requires immediate attention to avoid potential issues with the vehicle’s performance.

In this guide, we will delve into the causes of the P0602 error code and provide you with step-by-step instructions on how to fix it yourself. So let’s get started and get your vehicle back on the road!

Understanding P0602

The P0602 error code is associated with the Control Module Read Only Memory (ROM) and indicates that there is a programming error or malfunction within the ROM. The ROM contains vital information that controls various aspects of the vehicle, such as engine performance, transmission, and emissions. When the ROM malfunctions, it can lead to poor vehicle performance, including engine misfires, erratic shifting, or even stalling.

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The causes of the P0602 error code can vary, but some common culprits include power surges or voltage spikes, faulty connections, or a defective control module. Additionally, water or moisture ingress into the control module can also contribute to the error code.

Diagnostic Steps

Before diving into the repair process, it’s important to perform some diagnostic steps to ensure that the P0602 error code is isolated and not accompanied by any other error codes. Here’s a step-by-step guide:

  1. Check for other error codes: Use an OBD-II scanner to retrieve all error codes stored in the vehicle’s control module. This will help identify if there are any additional issues that need to be addressed.
  2. Inspect the control module connections: Carefully examine the connections between the control module and its wiring harness. Look for loose or corroded connectors that may be causing a poor connection.
  3. Check the power supply: Verify that the control module is receiving proper voltage and ground. Check the fuses related to the control module and ensure they are intact.
  4. Perform a control module reset: Sometimes, a control module reset can resolve temporary issues. Disconnect the battery’s negative terminal for a few minutes, then reconnect it to perform a reset.

Fixing P0602

If the diagnostic steps haven’t resolved the P0602 error code, it’s time to move on to fixing the issue. Here’s a step-by-step guide on how to fix P0602:

  1. Disconnect the battery: Ensure the ignition is off and disconnect the vehicle’s battery by removing the negative terminal. This step is crucial to ensure your safety and avoid any electrical mishaps.
  2. Locate the control module: Depending on your vehicle make and model, the control module is typically located in the engine compartment, passenger compartment, or under the dashboard. Refer to your vehicle’s service manual or consult an online resource for specific instructions.
  3. Remove the control module: Carefully detach the control module from its mounting location. Take note of any screws, clips, or connectors securing it in place and remove them accordingly.
  4. Replace the control module ROM: Once you have the control module in your hands, locate the ROM chip. Gently remove the old ROM chip by releasing the retention mechanism or carefully desoldering it, depending on the module’s design.
  5. Install the new control module ROM: Take the new ROM chip, ensuring it is compatible with your vehicle’s control module. Align the chip properly and secure it in place, following the manufacturer’s instructions. Take care not to bend any pins during the installation process.
  6. Reinstall the control module: Put the control module back in its original location and secure it with the screws, clips, or connectors. Ensure everything is tightly fastened to prevent any rattling or movement.
  7. Reconnect the battery: Reconnect the negative terminal of the battery. Double-check that all connections are secure before proceeding.

Tips and Precautions

  • Use caution when handling the control module: The control module is a sensitive electronic component, so handle it with care to avoid static discharge or physical damage.
  • Follow the manufacturer’s instructions: Always refer to the vehicle’s service manual or any specific instructions provided by the control module manufacturer for the proper installation process.
  • Consult a professional if unsure: If you are not confident in your abilities or lack the necessary tools, it is recommended to consult a professional technician. They have the expertise and experience to handle control module repairs effectively.


Fixing the P0602 error code associated with the Control Module Read Only Memory (ROM) is crucial to ensure your vehicle’s optimal performance.

By following the step-by-step instructions provided in this guide, you can address the issue yourself and save on costly repairs. However, if you feel uncertain or uncomfortable with the process, it’s always best to seek assistance from a qualified professional.

Remember, resolving the P0602 error code promptly is essential to prevent further complications and ensure a safe driving experience. Take care of your vehicle’s control module, and it will continue to serve you reliably on the road.


Q: Can I fix P0602 without replacing the control module?

A: In some cases, it may be possible to repair the control module ROM without replacing the entire control module. However, this requires specialized equipment and expertise. It is recommended to consult a professional technician to determine the best course of action.

Q: Is P0602 a serious issue?

A: Yes, the P0602 error code should not be ignored. It can lead to various performance issues in your vehicle and may even result in unexpected breakdowns. It’s crucial to address the issue promptly to maintain the optimal functioning of your vehicle.

Q: How long does it take to fix P0602?

A: The time required to fix P0602 can vary depending on your familiarity with the process and the specific vehicle model. It can take anywhere from a few hours to a full day, considering diagnostics, parts replacement, and reinstallation.

Q: Can I drive my vehicle with the P0602 error code?

A: It is generally not recommended to drive your vehicle with the P0602 error code. The error indicates a problem with the control module ROM, which can lead to unpredictable performance and potential safety hazards. It’s best to address the issue before resuming regular driving.