When your vehicle's computer senses a problem with a prominent piece of equipment such as the transmission or engine, it will send out a code to alert you. This will result in a warning light appearing on your vehicle's dashboard. After the repair is complete, however, it may still be necessary to reset your the computer in order for the warning light or lights to disappear. Fortunately, this process is fairly simple.
Open the bonnet of your vehicle. If the hood is not hydraulic, use your vehicle's hood stand to prop it open temporarily.
Loosen the nut that holds the negative terminal to the battery with the pliers. The negative terminal is labelled with a minus sign (-) or is black in colour; the positive terminal is red. Touching just the negative or positive terminal will not cause an electric shock, but touching both at the same time will.
Completely remove the cable from the negative battery terminal. This will disconnect the power from your vehicle's computer.
Leave the battery disconnected for 10 minutes to ensure that the computer is fully reset.
Reconnect the negative battery cable to the terminal and tighten the nut that holds it in place.
Close the vehicle's bonnet and start your car to check that the computer has reset and that the warning lights have disappeared.
- Car PC Hacks; Damien Stolarz ; Jul 2005