Doggone O2 Sensors/Cats!!! PO 440 , 441 & 446 (might NOT be sensors)
 

I'm just venting :D.....seems they went....so now I have to buy some. Merry Christmas to Mike:D

How do all your 02 sensors and cats go at once?
I was able to get original spec universal denso's for about $20+ for my LS .
Cats are hard to kill , something must be running real bad to do that much damage.

Mike,

First a couple of questions for you then some FYI's...

- How do you know that your cats are bad?
- Are you getting a rotten egg smell?
- What code(s) are you getting? PO430?

I was getting a PO171 (engine bank 1 too lean) and am now getting a PO430 (catalyst inefficiency condition) on top of that. Hoping that it isn't my cat because there is no smell coming from the exhaust I bought all 4 brand new OEM Denso O2 sensors. I paid around $290.00 at sparkplugs.com for all four O2 sensors shipped to my door!!! I am getting these sensors installed in a week or so. Perhaps you too want to go this route first before looking into a new cat...I heard it's a lot of $$$.:sad: GL!:thumbup:

THanks. I got the codes written somewhere. I am told by Lexus is the sensors and cats but no, my car does not smell at all.

I think I'll try the sensors first. THanks!:thumbup:

Come on , more details , what is it doing . You know we all know more than any lexus technician !

LOL

Seriously , all 6 parts cannot fail at once unless the car is on fire or the exhaust bolts are broken causing it not to ground and read the senors right.
If you can get a laser temp reader and aim it at each cat , it will give you an idea if it is working or not as the temp of the metal before and after the actual cat will be much cooler after driving the car for at least 20 minutes.

PO440 Evac Emissions Control System Malfunction
PO441 Evac Emissions Control System Purge Flow Fault
PO446 Evac Emissions Control System Vent Circuit Malfunction

Is this right? So its NOT a sensor or the cats? (see in bold)

http://www.fixya.com/cars/t1259066-p0440_p0441_p0446

These codes are all for the Evaporative Emissions System.

P0440- Evaporative emissions system fault- just saying there's something wrong with the system.

P0441- Evaporative emissions system- Incorrect purge flow- saying that the system isn't purging the raw fuel vapors (hydrocarbons- HC) as well as it should.

P0446- Evaporative emissions system- Control valve circuit low- there is a valve, usually located on the charcoal canister at the rear of the vehicle, that opens to allow fresh air to enter the evaporative emissions system as the engine vacuum purges the fuel vapors from the charcoal canister and closes when purge is not needed to prevent leakage of those fuel vapors to the atmosphere (HC is a greenhouse gas and is regulated as such by the fed gov't).

Given that you have the incorrect purge flow code and the control valve code together, my bet is that the vent control valve has failed (causing the P0446) and is not opening to allow fresh air into the system to displace the air from within the system that is being pulled to the engine. Since you have no fresh air entering the system, the engine will pull a vacuum on the system instead of the vapors "flowing" into the engine (causing the P0441).

http://www.toyotanation.com/forum/sh....php?p=2498342

Look out for Rust
Not a Scion, but a member of the Toyota family, my 98 Camry was getting intermittent Code PO446 indications which I would trouble shoot and then turn out the light to see if it worked. After a month or so, it would come back. Finally had to gas the thing up (it is my wife's car) and noticed all sorts of rust on the mouth of the gas tank filler. There was definitely enough there to affect the seal. Cleaned off the rust from the filler mouth and from the rubber seal on the cap and after a month, the check engine light is still out. Definitely an inexpensive fix. It looks like Toyota didn't figure that component needed plating.
I've noticed all sorts of Toyota products with recalcitrant problems in this area (Code PO446). The effect of rust on the filler mouth is the same as a bad or loose filler cap. I hope this info helps someone.
Machinbird is offline Reply With Quote

I then found this.
http://www.tundrasolutions.com/forum...-engine-light/

I'd like to know how they changed(adjusted) the values. Sounds like a load of BS to me. You cant change values of anything even with the Toyota scan tool. I bet they just cleared the code and sent you on your merry way.
You need another dealer who knows how that sysytem works and what to look for.
p0440/p0441/p0446 usually means there is a large leak on the Fuel filler side of the tank.
Causes could be : gas cap loose or aftermarket or not holding pressure.
OVERFILL CHECK valve in the top of the tank, they are known to crack.
Any number of hoses in the evap system may have come loose.
Charcoal canister may be defective.
The CCV valve would have been the first place to start as there is a TSB on that. The EVAP VSV is also know for sticking, and it is under the cover on the top of the engine.
If the gas cap is tight and not aftermarket, my next GUESS (i have no scan tool data) would be the overfill checkvalve. When it cracks it leaks fuel into the charcoal canister, when the canister gets full of fuel it will eventually leak into the rear crossmember and then onto the ground. They both should be replaced when this happens.
You really need to find someone who knows what they are doing.
Wish we could help more.

http://en.allexperts.com/q/Lexus-Rep...330-P0446.htmA

Hello Tami,
The P0446 is an evap code. There is a campain on this particular year. Usually the check valve on your charcoal Canister need a replacement. I would have a Lexus trained tech diagnost this problem.
On the P0330, What kind of gas were are using? Your knock located in the V-bank. Sometimes the knock sensor could goes out or connection is lose. Have a Lexus trained tech look at this problem also. Thank you.
JP Importz
Dallas Independent Lexus and Toyota
Service, Repair and Performance
www.jpimportz.org
214-221-3135

Found here :)

https://www.clublexus.com/forums/rx3...lfunction.html

Points to fuel cap.

My car is not leaking, it doesn't smell like gas, it doesn't have a rotten smell and it gets Premium fuel.

I want to fix this right, it seems people are told all sorts of things. I was told it was the O2 sensors and cats but that does NOT seem to be the case.

http://answers.yahoo.com/question/?q...5173319AABfE9W

Dang it.....well off to check the gas cap with a new one and go from there.

So I clean my K&N air filter, take off the neg battery cable, the ECU fuse and clean the crap out of the gas cap area. I then put in a bottle of STP Complete Fuel Cleaner and a new gas cap.

No check engine light.


I drive around and put some gas in the tank.

No check engine light.

Lets see what the Emissions guy says tomorrow :D

https://www.clublexus.com/forums/per...acement-2.html

https://www.clublexus.com/forums/gs-...****-made.html

GS Links I looked at.

i have the same issue with the 446 code..new OEM cap and still lit up..no gas smell or anything..would that mean check valve? is that cheap? easy to DIY? i aint tryna get a new canister..i heard those thangz are expensive!!