Found this online.. And tired of typing it to everyone asking.. So here you go
This is used for clearing codes by disconnecting the battery cable for 15 mins. Be sure there is no cell phone chargers/lap top/anything like that plugged in. While cables are disconneted i always cycle the key. And turn the head lights on. Then follow it up by the relearn process.
Because your vehicle’s engine is electronically controlled by a computer,
some control conditions are maintained by power from the battery. When
the battery is disconnected or a new battery is installed, the engine must
relearn its idle and fuel trim strategy for optimum driveability and
performance. Flexible fuel vehicles (FFV) must also relearn the ethanol
content of the fuel for optimum driveability and performance. To begin
1. With the vehicle at a complete stop, set the parking brake.
2. Put the gearshift in P (Park), turn off all accessories and start the
3. Run the engine until it reaches normal operating temperature.
4. Allow the engine to idle for at least one minute.
5. Turn the A/C on and allow the engine to idle for at least one minute.
6. Release the parking brake. With your foot on the brake pedal and with
the A/C on, put the vehicle in D (Drive) and allow the engine to idle for
at least one minute.
7. Drive the vehicle to complete the relearning process.
• The vehicle may need to be driven 10 miles (16 km) or more to
relearn the idle and fuel trim strategy along with the ethanol content
for flexible fuel vehicles.
• If you do not allow the engine to relearn its idle trim, the idle quality
of your vehicle may be adversely affected until the idle trim is
• For flexible fuel vehicles, if you are operating on E85, you may
experience poor starts or an inability to start the engine and
driveability problems until the fuel trim and ethanol content have been