You probably put an O2 sensor where you should have an Air ratio sensor, they are different they only look similar but they are different internally.
You need to a new oxygen sensor if you are getting a p1155 code on a 1998 Lexus. This means that heater circuit is malfunctioning.
Researched it, and found what DTC P1155 means - P1155 Electronic Traction System Limp Home Valve. Sometimes the symptom can be cured by checking loose connectors, wiring, rematching tires, properly inflating tires, etc. You may want to stop by your local AutoZone, Checkers, CKS, etc. and ask them if they have the valve and how hard it is to fix. CODE P1155 IS ELECTRONIC THROTTLE SYSTEM LIMP HOME MALFUNCTION NOT ELEC TRACTION SYSTEM. 3.5L SANTA FE HAS AN ELECTRONIC TROTTLE SYSTEM (DRIVE BY WIRE), THIS CODE USUALLY COMES ON WITH ANOTHER CODE. P1155 MEANS THAT THE ELECTRONIC TROTTLE SYSTEM WAS IN LIMP HOME MODE.
In my 2004 Sienna there was a weld in the door assembly that broke and caused a loud clunking noise when I opened the door. Toyota recently issued a recall for this problem and will fix it free of charge
replace oxygen sensor on the left bank(side towards front of car) it is located on the exhaust manifold staring you in face when hood is open Read more: Toyota Highlander Limited what does trouble code p1150 on - JustAnswer http://www.justanswer.com/toyota/490ow-toyota-highlander-limited-does-trouble-code-p1150.html#ixzz1T8tewlwW
fix the vacuum leak
The following link has instructions, diagrams and pictures showing how to make this repair easily and inexpensively: http://www.findonefindall.com/toyota-sienna/siennareardoor.htm
To fix a Toyota Sienna driver's side seat belt that is stuck, you might need to pull the entire belt out slowly until it is completely extended. Then, allow the belt to retract slowly.
We have a fix for this problem that anyone can do - includes testimonials! http://www.findonefindall.com/toyota-sienna/index.htm See full details under "How do I replace the passenger side mirror on 2000 Toyota Sienna?
http://www.findonefindall.com/toyota-sienna/siennareardoor.htm Works like a charm. I spent $497.00 getting my 1999 Sienna handle fixed at the dealer, less than 2 yrs later it broke again. This fix took less than 30 mins and cost pennies.
It seems that you need new tires.
How To Fix vsc,trac off and engine light on for 2009 Toyota Sienna
Get a new car................ -___-