Ok, I have a 2008 SR5 V6. Almost 300K miles. has a weird gas gauge issue and it ran out of gas recently. Refilled it and then got a pair of codes (P0420 & P0430) tried cat cleaning and O2 Sensor cleaning (several methods). Still get the codes. Wave forms on the Techstream show lots of variability, even when hot, on both downstream sensors. Lambda is either side of 1 (0.98 - 1.02, variable) on both banks, LT Fuel trims are less than +3% both sides. Upstream cat temps are 12-1300 +/_ and downstream are 10-1200, which matches 2 other known good vehicles with no CELs or codes thrown.
I can't find any online confirmation that running out of gas kills cats, but yet here i am.
I replaced an O2 sensor with a Denso from Rock Auto 1.5 years ago after it threw a code and the old one failed the checks.
I am about resigned to doing the Cats and with them the downstream O2 sensors, just cause of the mileage. Any ideas on narrowing this down? I am going to do the exhaust leak check tonight, but unless there is a leak between the two sensors (especially between the cat and O2 sensor) its not supposed to make a difference, right?
Guess my question is, every experts says, generally, that cats "last the life of the vehicle", and then talk about typical US car lives (less than 200K). For those of us that drive them past 300K, how long are the cats lasting? I have driven camrys, a sienna and this 4runner all past 300K and i have only one replaced a cat...on the sienna after an A/F sensor shot craps, slowly, and it ruined the cat.
And when I do the cats, i am looking at the usual aftermarket folks with 2 - 5 year warranties, which should be good enough, but who should I avoid?
Thanks in advance,
Jeff-in-KC