how to use a diagnostic scanner to clear codes on your car

Clearing Diagnostic Trouble Codes (DTCs) from your vehicle using a diagnostic scanner is an essential skill for both mechanics and vehicle owners. It helps in diagnosing and understanding vehicle issues quickly. Here’s a step-by-step guide on how to use a diagnostic scanner to clear codes on your car:

Step 1: Choose the Right Diagnostic Scanner

  • Basic Code Readers: Ideal for basic diagnostics, including reading and clearing codes.
  • Professional Scanners: Provide comprehensive diagnostics, including real-time data, system tests, and advanced troubleshooting.
  • Bluetooth Dongles: Offer a user-friendly interface through smartphone apps, ideal for those who prefer a more interactive diagnostic process.

Step 2: Locate the OBD-II Port

  • The OBD-II port is typically located underneath the dashboard near the steering column but can vary based on the vehicle model.

Step 3: Connect the Scanner

  • Plug the scanner into the OBD-II port. Ensure the vehicle’s ignition is on, allowing the scanner to operate.

Step 4: Read the Codes

  • Navigate through the scanner’s menu to find the option to read the stored DTCs. Document these codes for reference and further diagnosis.

Step 5: Clear the Codes

  • After noting the codes, locate the option on the scanner to clear them. Confirm the action and wait for the scanner to reset the codes.

Step 6: Check for Residual Issues

  • Clearing the codes does not solve the underlying mechanical issues. If unresolved, these could cause the codes to reappear. Additional diagnostic work or professional assistance may be needed to address these issues permanently.

Common Diagnostic Trouble Codes

  • P0300: Random/Multiple Cylinder Misfire Detected.
  • P0171: System Too Lean (Bank 1).
  • P0420: Catalyst System Efficiency Below Threshold (Bank 1).

Benefits of Using a Diagnostic Scanner Regularly

  • Preventive Maintenance: Helps identify potential problems early, avoiding major repairs.
  • Cost Savings: Early diagnosis can prevent minor issues from becoming major, saving on expensive repairs.
  • Improved Vehicle Performance: Ensures all vehicle systems function correctly, enhancing overall performance and fuel efficiency.


Using a diagnostic scanner effectively is crucial for maintaining your vehicle’s health and ensuring safe driving conditions. While scanners help in resetting the DTCs, addressing the root causes is essential for long-term vehicle maintenance and performance.


  • What is OBD-II?
    • A system that monitors the vehicle’s performance and checks for issues, storing DTCs that indicate performance anomalies.
  • How to use a scanner to clear DTCs?
    • Connect the scanner to the OBD-II port, turn on the ignition, read the codes, and use the scanner’s menu to clear them.
  • What to do after clearing DTCs?
    • Investigate and resolve the underlying causes of the DTCs to prevent them from reoccurring.

This guide should help you effectively use a diagnostic scanner to manage and reset the DTCs, contributing to better vehicle maintenance and performance.

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