jayclapp

This doesn't sound like a place I would want working on my Lexus. What did they suggest was the problem. Their work or a new area? Fixing a car and then delivering it with yet another problem seems a bit strange to me.

Boomer01

Hopefully the check engine light wont come on again. I've cleared my codes before, thinking the problem was fixed, only to see them come back the next day.

10suxel02

Did seem a little odd, but there is no engine light after multiple drives. They would have had to disconnect, and then reconnect, the two oxygen sensors, when they replaced the y-pipe, so maybe the computer had to have time to read all of the new information before it squared itself away, who knows.

The current status is no engine light, so everything is fine.

Thanks for all your support.

Boomer01

I got sick of seeing the check engine light on, so I took my car to the muffler shop. After reading this thread my assumption of an exhaust leak was confirmed. The muffler shop found a crack in the passenger side muffler around the second O2 sensor and welded it. It only cost me $20 and now I have no more check engine light.

StanVanDam

My 2002 had a P0430, and there were two causes: 1) a small gasket leak at the front of the Y-pipe, 2) a small crack in the passenger side of the Y-pipe, directly underneath the very front of the heat shield.

Every LS430 over 10 years old and driven on salted roads will develop this problem. The heat shields, heat shield clamps, and exhaust pipe are made of different metals, which encourages galvanic corrosion.

The mild steel heat shield clamps are in close contact with the stainless steel heat shields. This + salt quickly rusts off the clamps and cause them to rattle against the pipe. Because the stainless heat shields are in close contact with the mild steel pipe, I believe this also encourages corrosion of the exhaust pipe. With the clamp loosened, it is even easier for salt water to get inside the stainless heat shields, which burns off, and then the remaining salt encourages rusting from the inside.

See thread at http://us.lexusownersclub.com/forums...0420-on-ls430/

If you catch the problem too late, it will cost you $300-600 to buy and install a new Y-pipe. Cheaper to catch the problem early when the muffler shop can still weld the crack. If the crack is too deep/big, it is usually not possible to weld. You can get a brand new pipe+catalyst for the essentially the same price as having a shop cut off the bad pipe, fabricate a replacement, and weld the replacement in.

Also, don't bother reattaching the heat shields unless you do a lot of offroading and driving over dry grass.

CLMW

I recently got P0420 code on 02 LS430 due to a leak near left O2 sensor right where Y pipe starts. The dealer wanted $3300 to replace cats and entire exhaust. Took it to a local muffler shop which cut and welded a 4 inch pipe right where left O2 sensor is located. Didn't get the code after that. But few days later started noticing high pitch humming noise which was faint in the beginning but with time got louder. Initially thought it might be due to old tires. Last week got new tires and now I can hear the whining noise more clearly now. It is only there during acceleration and when the rpm goes over 2000. The noise goes away or is hardly noticeable as soon as I remove my foot from gas. The noise is there even in cruise control. Feels like an engine struggling when going uphill except it feels high pitch and doesn't feel like a smooth engine sound. Besides noise the car drives fine.
Took it to back to the muffler shop mechanic but he dismissed it saying that it is just engine sound which can be expected in an old car with 150k miles. It is not very loud but loud enough and high pitch to be really annoying on highway to give a headache. Took it to two other mechanics who could hear the noise but couldn't exactly pin point what was causing it. I feel it has something to do with the welding of new part in exhaust since this noise was not there earlier. Can anyone who has experienced similar issue suggest what it might be ? Should replace the Y pipe with an aftermarket or replace Y pipe and muffler ? It is hard to live with that whining noise. Any suggestions will be highly appreciated.

Polabareus

Ever figure this out? Could it have been a tiny hole/Crack the welder didn't get causing air to "whistle" out at certain speeds?