So Ive owned my 06 IS 250 for a year now. It is originally American.
I've noticed the whole rough idle thing since just a few months after I bought it. I always had the odd rough start but always noticed that rough idle randomly after stopping from highway speeds.

Just last week I had a really rough start and then my engine and Check VSC light came on accompanied by the really rough idle, worse than ever before, and it did it again when I turned my car on later that evening. I read the code and it was PO304 and thats when I began looking into it and noticed its a pretty fairly common and been recognized by lexus with the CSP which from reading other threads sounded like it was in effect in both USA and Canada.

So I called Heffner Lexus today, in Kitchener ON, the dealership that I would take it to if needed, told him of the problem and he didnt seem to have much clue of what I was talking about when I told him about the cylinder misfire and rough idling. I was expecting him to know exactly what I was takling about. He told me he has never had any complaints for rough idling and didnt know what CSP stood for. When I mentioned carbon build up he knew right away and said they can clean the engine but that would cost ME $800.00.

Not to happy about this as other seem to have had luck dealing with this in Canada and it sounds like its a pretty straight forward procedure in the states.

Looking for some help here, if anyone from Canada has gone through to deal with this can you explain how about you managed it.

Much appreciated. Thanks.!!

 

Pull out the mass air flow sensor and clean it out with carb cleaner, if that doesn't work than use the Lukas treatment on it. It really does get rid of the carbon buildup. Look up some YouTube videos on how to do it.

 

OP I'm from Waterloo.. you can also try Seafoam.. look up some threads/ vids for that as well