Da CaVeman

Car is due for inspection at the end of this month and went to get my cel checked out....Got the code P0420 for a "Catalyst efficiency low-bank 1" Probable causes:
1. Catalytic converter defective (Failure possibly due to #2, 3, or 4)
2. Engine misfire or running condition
3. Large vacuum leak
4. Engine oil leakage into exhaust-valve guide seals, piston rings

I don't think its number 2 because the engine is running smooth and haven't heard anything abnormal. As for the others, I don't know...

Anybody have any ideas???

Thanks! =/

VVT-i

It may help if you post your vehicle year,model and mileages. Bank 1 is the bank with #1,3,5 and 7, not the #2,3 or 4. Bank 1 is all the odd number, bank 2 is the even number.
If you do the search for this code, most likely it's your catalyst convector. Good luck.

mitsuguy

iTrader: (2)

+1 9 times out of 10, that code by itself shows that the catalytic converter is not working as well as it should.. there is the 1 in 10 chance that you have some o2 sensors not working properly, but typically that also sets other codes directly for o2 sensors...

depending on year and model of car and mileage of course, as noted, some different things can cause those issues... lean running, rich running, bad gas, gas with lead, oil in exhaust (leaking past piston rings / valve stem seals), unburnt fuel being dumped in the exhaust, and a few others...

all of the above problems take some time to really cause damage though typically... if you've got more than 100k on the car, I'd just say its the cat and be done with it... doesn't hurt to look into the other things just to make sure...

labrealiv

Hi Cave dude -

See if this link helps:

https://www.clublexus.com/forums/sho...d.php?t=340604

Da CaVeman

Oh, sorry...I thought my car info showed up in my signature....It's a 98' es300 with 184K mi. At this point, I might as well have my catalytic converter replaced anyway....I checked out my plugs last night...I have bosch platinum 4s put in about 3 months ago....the tips are now black and there is residue of a little bit of oil on the threads and at the base of the plug....piston ring leak?? =/

I appreciate the help fellas!

mitsuguy

iTrader: (2)

actually sounds more like its running real rich... black plugs = rich... oil at the bottom of the threads might mean a little bit of blow by, but, are you sure it's oil from inside the cylinder head and not down in the spark plug tubes (valve cover gasket leak?)

I would really think about changing plugs, those bosch +4's are not that great in the imports... better off with a NGK/Denso (copper if you're cheap and don't care how long they last, platinum if you want them to last 60k)

Da CaVeman

Yeah, I do plan on swapping my plugs out again after my inspection to the ngk or denso. This may be a dumb question but how would I know if its from inside the cylinder head or down the spark plug tube? My reasoning that it may be a gasket leak would be because the oil is on the threads at the opposite end of where the electrode prongs are.

mitsuguy

iTrader: (2)

flashlight... look down in the spark plug tubes and see if there is residual oil on the tubes themselves... this would indicate some seepage from the valve cover seals that falls down onto the spark plugs, which sometimes gets on the threads when you pull the plugs out...

Da CaVeman

Checked down the tubes...All are nearly spotless

mitsuguy

iTrader: (2)

probably just a little blow by... I wouldn't worry about it unless its enough to see coming out the exhaust...

Da CaVeman

Ok. I mean, it wasn't a lot of oil residue...Just enough for me to wonder...Igonna pick up the new plugs today to change them out. I'll check up on them at my next oil change and see. A friend of my dad is checking out the car today. He's an engineer/mechanic so he's gonna take some readings from my sensors and check out the cat.

Thanks for your input man. I really appreciate it!!

Da CaVeman

dad's friend just finished taking readings from the sensors with his laptop. Determined that my front o. sensor was not functioning..(Bank2 sensor1 is it?)So gonna call up the dealer and get a cost on the sensor...I am hoping this will be the problem and not the cat also....crosses fingers....

kingofire

Get the 02 sensor from ebay and have the dealer install it for labor only. Search for Denso 02 sensor.

mitsuguy

iTrader: (2)

If you are going to go that far as to get a probably inferior O2 sensor from ebay, then you might as well install it yourself... it's all of a 15 minute job, including jacking it up if needed instead of paying the dealer a half hour labor at prolly $100 / hour...

Da CaVeman

Thanks guys...Just to be sure, I think I'm just gonna pick up the oem sensor at the dealer and install it myself. I get a bit weary when it comes to aftermarket sensitive electrical components like sensors...One dealer gave me a quote for $297, the other for 167 WTF?!?! I have the sensor socket sitting on my passenger seat waiting to be used =) Gonna pick up sensor today and put them in along with the new plugs and hopefully all is good!

By the way, anybody know the proper torque spec for the plugs and also oil drain plug? I just got a torque wrench and plan on properly torqueing my work from now on...should have done this a long time ago =/ Acutally is there a master torque list anywhere? I know certain things are listed in the manual but not all...Sorry, I know I'm asking for a lot here