Your Toyota 4Runner can sense when certain problems occur. The vehicle's computer can generate a trouble code and activate the warning light on your dashboard. While that light is always disconcerting, it can be triggered by something simple, such as needing to replace the gas cap. No matter the complexity of the repairs, resetting the 4Runner's computer afterward is a relatively easy process. All you need is an OBD-II hand-held scanner.
Plug the diagnostics scanner into the port beneath the steering wheel. The scanner's cable ends in a 16 pin plug that should easily fit into an outlet with 16 receptors.2
Press the "on" button on the scanner.3
Insert the key into the ignition of the 4Runner and turn on the vehicle.4
Wait for the now obsolete trouble code to show on the scanner.5
Clear the code by hitting the appropriate button on the scanner. Most OBD-II scanners have a dedicated "clear" button, but if there's any confusion, consult your particular scanner's manual.