Short Term Codes

• 1
  The vehicle's direct current (DC) electrical system is powered by the car battery.dead battery image by Katrina Miller from Fotolia.com
  
  Locate the battery cable on the negative terminal post. This cable will usually be black.
  
  
• 2
  A crescent wrench can be used to losen the clamp bolt on the battery cable.crescent wrench image by robert mobley from Fotolia.com
  
  Loosen the bolt around the cable connection and pull the cable away from the terminal. Do not allow the metal on the negative cable to rest against any metal. Allow the cable to remain disconnected for 3 to 5 minutes.
  
  
• 3). Replace the battery connection. Error codes will be cleared, and dash lights and messages will be removed (such as check engine or the service engine light).
  
  

Long Term Codes (Reset ECU)

• 1
  Red-colored cables are used to indicate the positive terminal.closeup of jumper cables image by Katrina Miller from Fotolia.com
  
  Locate both the positive and negative battery cables. Remove the negative cable, then the positive cable and move them away from the terminals.
  
  
• 2
  Depressing the brake pedal to turn on the brake lights will drain power from the electrical system.brake lights close-up image by Kathy Burns from Fotolia.com
  
  Turn the ignition key to the electronics mode. Depress the brake pedal for 30 seconds. The ECU long term memory is electrically sustained by capacitors when the cables are disconnected. The remaining power in the electrical system, including the capacitors will be discharged by the brake system. The horn may also be used to discharge the capacitors. Leave the battery cables disconnected for 15 minutes to ensure all electricity is cleared from the ECU. Replace the battery cables.
  
  
• 3
  Driving your vehicle under normal conditions after resetting the ECU will allow the computer to optimize the engine settings.traffic image by dinostock from Fotolia.com
  
  Drive the vehicle, if possible, for 20 minutes under normal or expected driving patterns. Turn on all devices expected to be used (air conditioner, stereo, headlights, etc.) to allow the ECU to relearn the driving conditions and alter the engine parameters accordingly.
  
  
• 4
  traffic image by dinostock from Fotolia.com
  
  

Specific Error/Warning Code Clearing

• 1
  The OBD-II reader port is typically located under the driver's side dash.steering wheel and dash of british sports car image by Bo Widerberg from Fotolia.com
  
  Connect an OBD-II reader cable to the OBD-II port (driver's side under the dash on most vehicles equipped with OBD-II readers).
  
  
• 2). Turn the ignition key to the electronics-only mode. Turn the OBD-II reader on, and acquire the ECU codes. This may require accessing a menu setting depending on the reader used. Refer to the OBD-II reader instruction manual for specific steps.
  
  
• 3). Review the codes by scrolling through the list and select the code to be cleared.
  
  
• 4). Clear the code. This may require selecting "OK," "Yes," or "Enter" when asked if you wish to clear the code. The code will be removed from the ECU memory (permanently, if the underlying cause has been addressed, temporarily, if the cause remains).