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2004 RX330 160k with P0420/P0430. Fuel mileage was good (22 combined). I started with cleaning the throttle body, MAF, new air filter. I then replaced all the vacuum lines. Still came on after a reset.i tried all the fuel treatments as well. I actually removed the front catalytic converter (bank 2) & soaked it in dish detergent overnight. It was fully intact & appeared to be in good condition. I found that my valve cover was the old design found in the rx300's & replaced it as there was oil in my intake. The new baffle design remedies this. I also changed the spark plugs. Still nothing. Throughout all this the miles driven kept increasing before the CEL would come on. My last fix was replacing the downstream O2 sensors. All 4 were moving like they're supposed to, but given the mileage, I guess they were toast. After 40 miles the cats finally check OK on my readiness codes!
Last edited by Gmachine; 11-13-15 at 03:42 PM.
Reason: Found my problem
My Indy Toyota mechanic gave me some personal advice on replacing your catalytic converter. Only replace them when you don't pass smog. Just reset the code if you don't like seeing the codes. He got another 50k miles out of his cats before he failed smog.
Or you can do what Scotty recommends on this video. Since I live in CA, I couldn't get a high quality solvent like Naptha so I used 4 cans of Berryman B-12 Carb/Fuel Injector cleaner to 1/2 tank of gas and drove the car hard on the freeway. Feels the like the car is running on jet fuel or 100 octane gas. Berryman B-12 is a high quality Solvent Fuel injector cleaner. Your oil will be dark from all the carbon burnoff so it would be a good idea to get an oil change afterwards. After a few treatments, my codes never came back. Its been 9 months now. Give it try, sure is a lot cheaper than replacing your cats.
Thanks, I've tried Garaunteed To Pass once & 1/4 can of Seafoam too. The car still averages 22MPG, So I figure they can't be too dirty/clogged. I'll take a look at these videos & see about trying another chemical treatment. I sure can't find any exhaust leaks. The PCV has been replaced, throttle body cleaned & MAF cleaned. I've cleared the code three times now & did a 1300 mile road trip a month ago filling up with premium at every stop. Looks like it takes 200 miles before all the readiness codes show a P0420/430.
It's at 1/2 tank (9 gallons) so I added 1 gallon lacquer thinner to the tank. We'll see if this helps at all. The car has 160k on it, but you wouldn't know looking at it.
I suggest cleaning the cats with water....thru the vacuum booster hose. Look it up on google. Just did this and my mother in laws cats cleaned so well that the emissions were lower on her Camry then when we bought the car used with 180k miles. The technique is to have a helper hold engine speed at 2000 rpm and let the vacuum suck the water just enough to make engine stutter and clamp hose with a close pin so that it runs smooth for about 5 minutes. It essentially steam cleans the cat.
It's at 1/2 tank (9 gallons) so I added 1 gallon lacquer thinner to the tank. We'll see if this helps at all. The car has 160k on it, but you wouldn't know looking at it.
I know that some Lacquer Thinners are stronger than others. The ones in CA are weak due to the more stringent air pollution controls we have here, we cant get Naptha which is the main ingredient in Seafoam. Hopefully the thinner you got is a strong solvent. If not, I know that Berryman B-12 works.
I tried lacquer thinner twice (1st was from Walmart, 2nd automotive paint store) & drove 120 miles, p0420/430 both came back on. Tried Barryman B12 as well & nothing.
Yesterday morning I pulled the front cat & soaked it in dish detergent for 26 hours & soaked the air/fuel & O2 sensor for the front cat in gas as well. I then rinsed it out with a hose. The bottom part of the converter appears good & a flash light confirms the cells are clear. I boiled 5 gallons of water before adding soap & soaking the converter. I figured temperature would help. Once it cooled I emptied the bucket & made a fresh dish detergent soak. Dawn was the brand of soap.
I'm hoping I can avoid replacing both cats. The front one was easier to get to. This is my wife's car so her running the kids around may take some time to run through the readiness codes. If it comes on again for the front inefficiency, I'm taking it to someone & make sure that my Dash Command App is reading the fuel mixture before & after the cat the way I'm seeing it.
After soaking in dish detergent & soaking the O2 sensors in gas overnight & reassembly with new gaskets I still have the same P0420/P0430. I've replaced all the vacuum lines on top of the engine as well. I'll check the fuel trims next. Turns out this app can do this as too.t
My latest rabbit hole has me ordering a new rear valve cover due to oil in my intake via PCV. This was a large problem on the RX300's & they supposedly upgraded the rear valve cover internal baffle design & this fixes the oil consumption issue. Mine has what appears to be a 1st gen design valve cover. I found one on Amazon so we'll see what this fix does.
The Amazon OEM Toyota part was correct & only cost $112 shipped. Everywhere else I looked it was $190. It's on now & im only getting a P0420 code now. Both my pre-cat O2's seem to be bouncing around properly. I may remove bank1 post cat sensor & soak it in gas overnight.
I'm learning here, so any help would be nice. This is a screen grab at 2500RPM in Park
I'm not sure why my long term fuel trim is reading like a air/fuel ratio. This at 2500RPM in Park.
Based on your bank 2 fuel trim and your bank 2 sensor 1 voltages it looks like bank 2 is running lean and the system is correcting for it (vacuum leak is possible cause) or you have a bad air-fuel sensor making the system think bank 2 is running lean.
Your bank 2 sensor 1 ( air fuel sensor) voltage is generally higher than bank 1. Air fuel sensor voltage goes up as the mixture gets leaner. The high long term fuel number is an indication of the engine adding extra fuel to correct for the lean condition (real or caused by a bad sensor).
I had to replace an air fuel sensor on bank 1 ( under the car) Bank 2 is a lot easier to access, it is in the front of the engine compartment, accessible from the top.
Based on your bank 2 fuel trim and your bank 2 sensor 1 voltages it looks like bank 2 is running lean and the system is correcting for it (vacuum leak is possible cause) or you have a bad air-fuel sensor making the system think bank 2 is running lean.
Your bank 2 sensor 1 ( air fuel sensor) voltage is generally higher than bank 1. Air fuel sensor voltage goes up as the mixture gets leaner. The high long term fuel number is an indication of the engine adding extra fuel to correct for the lean condition (real or caused by a bad sensor).
I had to replace an air fuel sensor on bank 1 ( under the car) Bank 2 is a lot easier to access, it is in the front of the engine compartment, accessible from the top.
I updated my readings & gauges & recorded the latest while driving. I still think your opinion is correct.
When my air fuel sensor failed, the sensor stopped responding. It stayed around 3.3-3.4 volts and would not change with rapid changes in throttle position. The fact that your sensor appears to be responding, might point to something other than the sensor.
Can you monitor MAF voltages or flow rate with Dash Command? That might help you diagnose if the MAF is operating corrcectly.
When my air fuel sensor failed, the sensor stopped responding. It stayed around 3.3-3.4 volts and would not change with rapid changes in throttle position. The fact that your sensor appears to be responding, might point to something other than the sensor.
Can you monitor MAF voltages or flow rate with Dash Command? That might help you diagnose if the MAF is operating corrcectly.
Yes, I believe I can. I'll give it a try & see what I get.
09-24-15, 08:06 AM
Rx330 P0420/P0430 solved
