Hi all, I have an 03 ES300. 77,000 miles that I received from a friend's father. He gave me the car because the lower radiator hose clamp fell off from metal fatigue and the car overheated and caused the head gasket to leak. His mechanic said it wasn't worth fixing and he should junk the car, that's how it came into my possession.
I replaced the bottom clamp flushed the radiator system and added a bottle of gasket sealer. I drove the car around the block for about a month every couple of days to make sure the fix held.
I then registered the car and on my way to driving it to get the inspection done the check engine light came on. I drove to my mechanic who was going to do the inspection anyway and he informed me that the code it was throwing was one of the knock sensors. He said he could shut it off and maybe it doesn't come back and I had to drive between 50 and 75 miles to reset the computer in order for an inspection to be performed.
The cel came back on within a couple minutes. I then bought a code reader just to get it out of limp mode so it was drivable. I was doing this every couple of days and sometimes every couple of minutes. No rhyme or reason.
Not wanting to go through the expense of replacing the knock sensor I turned to the club Lexus forum and discovered a hack that tricks the computer into thinking that the sensor is okay. I performed the hack at the ECU and it worked!
However I discovered a problem with the heck. When the cel went on because of knock sensor it also disabled the VSC and traction control. I didn't discover this until driving the car in the rain and especially the snow. It was almost undriveable.
So after this very long-winded explanation because I wanted everyone to have all the information, I'm wondering if anyone has had the same problem and can offer a solution? Thanks for sticking with me!
Tom

 

VSC and traction control are disabled when most codes(s) are present. You'll have to ask a Toyota engineer exactly why although I can speculate.