To plug in a code reader on a 1998 Lexus ES 300, locate the OBD-II diagnostic port, which is typically found beneath the dashboard on the driver's side, near the steering column. You may need to remove a cover panel to access it. Once you find the port, simply connect your code reader to it and turn the ignition to the "ON" position without starting the engine to read the codes.
Pulstar
SPARK PLUG GAP2001 Lexus GS300 3.0L SFI DOHC 6cylThe Spark Plug Gap.044 (In thousandths of an inch)
92 Lexus is OBD 1. There is a plug for Lexus OBD 1, and will not work with an OBD2 scanner.
Trouble code P0420 means:Catalyst system efficiency below threshold
if the code is not located with your owners manual, go to a Lexus dealership to get a code. they may charge you for it.
The Lexus ES 300 is front wheel drive and the Lexus GS 300 is rear wheel drive
http://my.is/forums/f67/is300-changing-spark-plugs-340989/
See http://www.lexls.com/tutorials/lighting/airbaglight.html Instructions work for Lexus GS300 too, but diagnostic plug is in the engine compartment.
Trouble code P0401 means: Exhaust Gas Recirculation Flow Insufficient Detected
it requires gasket.get it from Toyota dealer.cost $1.50
yes 1mz-fe
Trouble code P0125 means: Insufficient coolant temperature for closed loop fuel control