I HAVE A 1998 LEXUS GS300 (126Kmi) WITH A CHECK ENGINE LIGHT, I CLEARED THE CODE AND IT CAME BACK, IM GETTING: P0155 HEATED OXYGEN SENSOR CIRCUIT BANK 2 SENSOR 1. I WOULD LIKE TO TRY AND REPAIR THIS MYSELF. CAN ANYONE TELL ME WHERE IN THE CAR THIS O2 SENSOR IS LOCATED SO THAT I CAN GET TO IT? AND IS THERE ANYTING ELSE THAT NEEDS TO BE REPLACED ALONG WITH THIS SENSOR??
My 99 GS300 Just turned 100K with the same symptom. I'm going on a trip to check the gas mileage...it appears the dealer doesnt change these things with scheduled maintenence as I reviewed 9 years of expensive maintenence bills and do not see a thing. Mine has two........ both visable from under hood on right side....one in front of the header cat and one behind. Ibelieve it is DENSO (Toyota) Part Number 234-4209.....$44.99 ea at oxygensensor4less.com My friendly lexus dealers want $129 or more which is typical for them.
The third one further back goes into the large cat just under the front door jam...haven't researched the part number of thi one yet, however it appears the same.. mine are four wire sensors (they preheat)...... one & two wire models will work but not till the exhaust heats up to 600 degrees.
Also visit www.autotap.com/OXYGENSENSORSppc_oxygen_sensors.html
Good Luck...let us know how you make out.
Jim in Kalamazoo