I have tried all the mentioned solution attempts and nothing is working. Can't play or eject any of the 6 cds in the player. On play the radio

 

Just fixed mine. There was a jammed CD. I had to remove the radio unit, which was not too difficult...here are instructions.. http://us.lexusownersclub.com/forums...oval-tutorial/
One out, you need to remove the outer brackets and then every little screw in order to take off the outer shell of the CD housing. The silver plate above the top CD in the unit can be lifted, and then carefully remove the CD. You need to move the CD around the little pegs or stems. Once that was done I plugged the unit back in to make sure that it worked before re mounting it. Mine did work and the problem was solved.

 

Yes I also had an error 4 come up on the cd ,it kinda went away for a while and after I replaced my battery it came back and I tried the disconnect the battery for 5minutes and remove the radio fuse,to no avail.So I got on the threads here and saw how to remove the radio,very easy - pull the gear stick cover off as well as the narrow one above it(holds the lighter)-both are just clips,then you will see the radio has 4 10mm bolts securing the radio( need an extension socket preferably with a magnet so you don,t lose the bolts,I also put a cloth in their to catch the bolts just in case!
The radio then pulls out easily and I pulled the plugs out and I gave the whole radio a blow out and a few taps with my hand to shake it up a bit, now I had 6 proper commercial cds in their at this time.
I plugged the radio back in and bingo all of a sudden the error had gone and I could remove all the CDs .for now I only put one cd back in ,I put the radio and panels back on ,all ok touch wood.i know it's not the most technical fix but it worked so....give it a try only took an hour and cost me nothing

 

Check out the postings by jakenbake in the forum posting linked below:

https://www.clublexus.com/forums/rx-...error-4-a.html