It's just the way the dealer's repair process is guys. They aren't "mechanics", they don't troubleshoot problems. They just replace stuff until they replace the right stuff. Like I said, it's fine when Lexus Is paying.

You both might be correct. I actually know the people at Lexus very well. Typically, they don't try to cheat me. I am their 2nd biggest customer - over 27 years, I have purchased 28 Lexuses and currently own LS 460, LS 600hl, CT 200 and RX 350.
I asked the general manager to personally look into this to see if there is an alternative solution.
I will know in a few days.
If they are unable to convince lexus to give the part for free, I would probably buy the part from Japan.

I am told by Lexus that if I don't fix it, my car will fail emission. Is that correct?

It's not about them wanting to or trying to cheat you at all. It's just the way they approach repairing a vehicle vs how an independent mechanic does. They don't do a lot on older cars, most of their work is maintenance, brakes, warranty work, Etc. Troubleshooting a vehicle and improvising a cost efficient repair are not in their skill set.

You are probably right.. but I am not sure what else I can do about it..

I would do some research into independents that service hybrids. Maybe check out PriusChat.com and see if there's anybody anywhere near you that might be able to look at it.

My independent mechanic is a hybrid tech...but obviously I'm not anywhere near you...

It's very hard to point you in any direction without having the trouble codes, so if you want to investigate further you have to get them. Your problem seems very specific to the hybrid and that part might actually be related to the SULEV II classification to the vehicule. If you read this: http://pressroom.lexus.com/releases/...fined+ride.htm

And this in particular: "A specially developed Hydrocarbon Absorber and Catalyst System is linked to the two-way exhaust to help prevent hydrocarbons contained in the exhaust from being released into the atmosphere during cold start up when the catalysts are not up to temperature. The LS 600h L also meets the Super Ultra Low Emission Vehicle II (SULEV II) certification."

What this mean is that if you don't do the repair your vehicule might still pass emission but loose it's SULEV II classification which was mostly developped to give the "green" image of the car by going the extra mile to reduce emission and sell it to people like Paul Mccartney. I guess you could compare it to subaru "PZEV". Subaru without it obviously pass emission, but those with it release even less emission. It's very sad they the own peoples at the dealership don't know anything about this car. Like SW15LS said, dealer sell car and parts, they don't repair stuff and I realized first hand that if your problem require them to use computer for tuning or diagnostic you are on your own because they only know how to change parts. Can they even point you at the part they call "Hydrocarbon Switching valve" ? Cause it's certainly not the whole exhaust system. If you don't do your homework nothing is preventing them to charge you 5k for a blown fuse. Not too long ago while working on my car the battery got so depleted that I had to jumpstart it. After that I had the all kind of light complaining about Parking Brake failure, VSC, ABS... Hooked my techstream computer and checked live data to confirm everything was working properly, cleared the code and never had a problem since. If I would have gone to the dealer trust me they would find a way to give me a bill of several thousands saying the ABS valve or actuator needed to be change. People said it numerous time battery failure cause havoc in those car. Your problem is probably different but I would first make sure nothing is wrong with the 12v battery or at least the fuses.

Good post. I will not get it fixed, until it fails emissions. I cannot believe that there is any "hydro carbon valve" in the exhaust system - because I don't know whether there is an electrical connection for the switching.

I think in California, if a CEL is on, it will auto-fail, even without the gas sniffer. Or maybe it's a CEL for emissions. Not sure.

Might want to check your air resource board, or whoever administers the SMOG check to see.

good point

If you have less than 80k miles on the car, it's covered under the federally-mandated emission parts warranty.

Unfortunately, I have 90k

Any update on this issue

I called Lexus customer service. The dealer also talked to the local lexus area manager. They gave $2500 off the cost of the part. I am getting it done.. because i don't know whether the car would pass emissions without this repair.

Try to get more discount. You have other cars to drive don't you

Keep fighting. I had to keep at it after my hybrid battery failure..ended up getting 75% off but I still felt it should of been 100 % goodwill based on my circumstances. I sold my 600 right after and your post is another reason why I'm glad I sold it.