My wife had the oh so familiar "Check VSC" "!" and Check Engine lights pop on. No unusual or noticeable changes in the way the car drives. Drove it for a few weeks until it was due for an oil change. Here is the print out from Lexus of Portland
"Found code PO420 stored. Bank 2 converter threshold malfunction. Monitored air fuel sensor and oxygen sensor operation. Completed troubleshooting flowchart tests, confirmed bank 2 converter is bad. need to replace cat converter".
We were quoted $2K to replace the converter. I questioned the possibility of a faulty or failed gas cap and that I'd like to go ahead and throw a new one on. The service rep assured me that my cap was fine and the code specifically pointed at the bank 2 cat and that buying a new cap would just be throwing money away. I was already into them for a little over $1200 for a oil change and front wheel bearing, so I didn't question throwing any more money away. They cleared the codes which popped back on with in 50 miles. About a week went by and all the lights turned off on their own and have been off for a couple days now.
Currently 110K miles
To be continued........................

 

why are you starting another thread? it is hard to track it then... you should be posting under main vsc thread.

 

There are several "VSC" threads. The latest thread by dscodogg69 was finally diagonosed as faulty battery concluding his post. I suppose I could continue on the same post, but most people won't thouroughly read more then a few pages if the symptoms don't relate to their problem. Hopefully, somone will have the same symptoms and be able to reply with a helpful post.

 

Lights came back on last weekend. I opened the gas cap and it did seem extremely loose, so I pulled the o-ring and turned it over so the worn flat spot is in the back. Dumped in a can of Sea Foam and the light went off two days later (light off 11-08)

 

Mine is bank 1, changed O2 sensor was fine for like 2 weeks, but light came back on took it to 2 different shops they ran their diagnostics and both said same, its the cats, so set up schedule with dealer, though my car is out of warranty the cats arent, fed mandate has them warrantied up to 7 yrs / 80k miles. Well ill keep you all advise to see what the dealership is going to try and sell me on

 

Whats with all these cats going bad yo?

 

Thats what im saying were forced to use premium gas and this happens