p0420 and new o2 sensor?

i recently installed my jba cat back and a new bosch oem style o2 sensor. today as i was driving i popped a p0420 code, a catalytic converter not being "efficient" i believe. the guy at autozone said that with a new o2 sensor (its downstream) it can take up to 100 miles before it breaks in and the cel will go away. any truth to this? if not what should i do?

 

honestly.....its probably the bosch o2 sensor. they just dont do too well on our trucks. oem type densos/ngk work best.

 

damn i thought it wouldnt matter since it was an oem style but denso was like 185 bucks

 

yeah...they aint cheap. try rockauto.com.....their prices are alot cheaper than the dealer.....and they are oem.

 

alright ill see if i can fix up my current situation idk what to do with a brand new oe style bosch sensor that just ran me 85 bucks but they definitally do have better prices at rock auto thanks for the advice

 

DENSO Part # 2344189, this sound familiar? or is it a different part number?

 

anytime man. with the bosch sensor...maybe put it on craigslist or just keep it for a back up.

 

for the rear(down stream) sensor...thats the right one.

 

just reset the ecu and got rid of the cel if it comes back on i may look into a denso thanks for the help

 

so i was under the truck today and had another thought. my shiny new piping is getting black and discolored for a bout a foot or two after the cat. i dont care so much about the discoloration, but could it be a sign of a clogged or blown cat? the po420 is listed as a catalytic converter deficiency or something of the sort. i know that bosch may not work amazing with our trucks but it is an oe type and i cant imagine that just that would throw a cel, or would it?

 

i've seen them throw codes right away. but.....with the piping getting real sooty......could be running really lean, which a clogged cat can do. if a cat is clogged tho.....the truck will bog down when you get into the throttle while you are driving it...especially when it gets heated up.

 

truck still performs like a champ, unless my definition of bogging down is different then yours. idk if its soot or just discoloration, wouldnt soot have more of a texture to it? i may be able to get a picture up once i find my camera. ill take the plunge for a new denso o2 but if that doesnt work and it really is the cat can i just run an o2 simulator? will that affect performance, ratios etc? btw thanks for all the help man its much appreciated

 

im guessing its probably just discoloration....that will happen quick with new piping. and the o2 sensor sim is a good diea....its a one time fix for good for that sensor.

 

my only worry about an o2 simulator is whether or not the a/f ratios are being monitored behind the cat. i guess what im asking is whether the rear o2 sensors only purpose is monitoring emmisions or will plugging in a simulator mess up anything vital (or somewhat important) to the engine

 

lol alright thanks guys

 

alright thread revival time. I got my denso sensor in the mail the other day and installed it. all was good. The cel came back on today it was too late to go get it checked to see exactly what it was but im thinkin it was the p0420 again, ill get it checked tomorrow. another thought is that the jba threads for the sensor blow and are already stripped out so i couldnt bolt one bolt all the way down but the other one is pretty tight on there. my ghetto fix was to hook up the old bosch sensor and leave it under the seat and keep the denso one in because of the stripped bolts. any detrimental side affects of this? i just did it tonight so i wont be able to see if itll keep the cel away assuming its the p0420

 

anyone?

 

most likely you have a bad cat. If the sensor was bad it would set a code for the sensor not the cat. In order for it to set a code for the cat, both sensors have to be working properly. o2 simulator would be a good fix because the first sensor is what the engine uses to moniter a/f mix. Second sensor is only there to check the cat. Be careful with that sensor under the seat. It wont hurt anything electronicly but they have heaters built into them and they get pretty hot. Ive been working as a tech at a toyota dealer for about 12 years now and i have never seen a cat clogged before so i doubt that is a problem. That just doesnt really happen because of the style cat toyota uses.

 

Hi!!

I've been reading A LOT on this P0420 problem and found out a few good thing you might like to know!!!

I lot of people have the same problem that we do, some changed everything related to emission system. Cats, o2 sensors, MAF, MAP, Temperature Sensor and still had the light coming on!!

On thing that not a lot a people think of checking is the Ethanol rating in the gasoline they use!! Toyota tacoma are set to use Gas with less then 10% ethanol... So what i did is I empty my tank and filled it back with ethanol Free Gasoline, unplug the battery to erase the codes and Guess what, no more light...

The problem with ethanol is that it doesn't burn like regular gas at all and our O2 sensors do not reconised the exhaust gas so your check engine light turn on!!!

I was using Gasoline that had 12% Ethanol and didn't know it!!

Try that and let me know what happens

Thanks