2008 GS350 - 129k miles - 1 owner
Looking for input on whether/how to proceed as this is now a multi-year problem (2019- 2021).

My 2008 Lexus GS350 had the following recalls (All fuel and engine related):
NHTSA CAMPAIGN ID: 18V432000
NHTSA Campaign Number: 14V647000
NHTSA CAMPAIGN ID: 09V020000
NHTSA CAMPAIGN ID: 10V309000

Before the last fuel assembly recall work was out of warranty, I started experiencing an extreme fuel odor after a decline on a 7% grade, once car levels out, AND each time car was started (noticeable only with windows down).

Went to 3 Lexus Dealerships. The first 2 didn't check the fuel injectors (and locked keys in car, prying at front doors as evidenced with scratches and green tape on one side). 3rd one checked warranty work because I got Lexus Headquarters involved but they claimed to find nothing wrong.

Before giving up on the car, as it ran beautifully aside from the extremely concerning smell (recall paperwork speaks of fire hazard, yet Lexus unconcerned), took it to an Independent mechanic who found a leaking fuel injector (port on that side is "clean", I have pictures.)

Took car back to 3rd Dealership as the fuel assembly recall includes touching fuel injectors and they "could not identify or see any leaking fuel injectors". Provided them the pictures, etc. and still claim nothing. I paid Independent mechanic to replace leaking fuel injector as I'm not interested in catching fire regardless of whether Lexus feels it should cover its work. No change in fuel smell, strong as ever.

Pandemic happened and I only drive the car once a week to the grocery store, strong fuel smell on startup still happens. (Haven't been on any incline/declines).

Mother's Day, I filled my gas tank up, started car, made 2 stops before heading home and "Check engine, Check VSC" and a myriad of lights came up on dash. (Total of 3 startups after filling tank, lights came on after 3rd start).
Code comes up - P0430 - Catalyst System Efficiency Below Threshold Bank 2

All the fuel related symptoms & issues can't be a coincidence. 2 Fuel assembly recalls, leaking fuel injector, fuel smell, now catalytic converter issue even though car is barely used in the last year.

I'm extremely disappointed in not getting any help from Lexus. They know they have fuel related issues with their cars, everything else is running just fine before and after they touched fuel assembly. ONLY issue I've had with this car is fuel related.

(Look at the fuel smell complaints here: https://www.nhtsa.gov/vehicle/2008/L...AWD#complaints)

 

Is this an AWD or RWD? If this is AWD, then your issues more likely is from the mid pipe rusting out because of a poor design. AWD's have a metal tin covering the exhaust mid pipe's. Inside the tin is a fiberglass matting and it absorbs road salts that internally rusts the exhaust pipe allowing pin holes, and exhaust fumes to escape. This could be the reason why you are getting foul odor, and also explains why your getting a bad catalytic code.

What many of us do is just take it to a muffler shop and have them completely remove the tin covers on both sides of the mid pipe. Then test the exhaust for any leaks. Many times the muffler shops will need to weld those pin holes or if the rust is to far gone, a section of tube will then need to be cut out and replaced.

 

You have a pin size hole in your exhaust under the heat shields that covers the exhaust manifolds in the mid section of the car. After the catalyst converters. I had this same problem 2 years ago. I also changed the O2 sensor in the same area (BANK 2 SENOR 2) which the heater element was burned out.

 

It is RWD.

 

It has been checked for leaks in attempting to address original issue.

No leaks found previously, O2 Sensors reported no issues. (Would this error code be reported if O2 sensors were bad?)

I've already sunk over $1000 into the car to remediate the fuel smell which changed nothing at all.

 

P0430 usually means your Catalyst convert is clogged, however I found out on my GS430 that a pin size hole was in fact in my exhaust mid section under the heat shield as mentioned above that caused my P0430 code. Dealers are not good at diagnostics with exhaust systems like a muffler shop.

A week after welding the hole, my bank 2 O2 sensor #2 heating element went bad, in which I diagnose with a multimeter

 

Thank you for your reply. I just learned my cousin's 2007 GS350 with 130k miles is doing the same as mine with the severe fuel smell on start that lingers for 1-2 minutes when driving. In addition, he's getting the rotten egg smell. Lexus, this is a design flaw and you know it. Everything else on these cars is in great shape even if they are 13/14 years old. The mileage is not high.

 

My 08 gs350 rwd 124k miles is throwing the same code P0430 (Cat system efficiency below threshold bank 2). I replaced both o2 sensors on the driver side and cleared the code. Code came back after about 46 miles. Decided to try a "cleaning" did both seafoam (intake) and kataclean(spelling?) in gas tank with just under ¹/4 tank, reset the code and its back again.. I then jacked up the car took the heatshield off the midpipes (behind second o2 sensor), plugged up the exhaust and pressurized the system to about 25psi with an air nozzle. Then sprayed down the exhaust with dish-soap/water solution looking for leaks. No leaks found... Any help here would be great because Im running out of ideas here and my tags are up this month, cant pass with check engine light on.... HELP

 

I have a 2005 LS 430 that has the same rotten egg smell when accelerating fast then goes away within the 1-2 minutes.

 

Did you ever get this solved?

 

Same thing on my 2007 GS350 AWD