which 02 sensor? code 420 on 96 explorer 4.0?

[porshapower]

Getting a code PO420 (CATALYST EFFICIENCY BELOW THRESHOLD..Bank 1). I know bank 1 is passenger side but I see 4 02 sensors all together. 1 sensor on driver side coming down off manifold another 1 on passenger side coming down off manifold. Then there is one that looks like it screws into the catalytic converter and another after the catalytic converter. Autoparts sold me the one before catalytic converter just want to make sure before I switch it. This is on a 1996 4.0 explorer. Thank You!!Nelson

 

[spindlecone]

how many miles on your ex?

 

[porshapower]

98kmiles. Thought the cats were bad. Hollowed them out last night

They were very clogged... Now the truck runs 100% better but got the 420code after about 3hours of driving. THanks

 

[spindlecone]

They were very clogged... Now the truck runs 100% better but got the 420code after about 3hours of driving. THanks

Well if you did that, me thinks you will now need an O2 sim, the code will not go away

 

[porshapower]

What is an 02 sim?

Thanks for the help!! What is an o2 sim?? Thanks again..Nelson

 

[spindlecone]

Thanks for the help!! What is an o2 sim?? Thanks again..Nelson

Simulator, ebay about 50 bux, the cat O2 sensor sends nothing to the PCM, until it senses a problem with the cat, clogged or missing in you case.
The sim is a dummy, the PCM thinks all is well= no codes

 

[porshapower]

Thanks again.. Is this a plug or??

Does it plug inbetween the plugs that connect the o2 sensor to the wire harness for the truck? Which sensor would I plug it into? THanks..learn something new everyday

 

[spindlecone]

Does it plug inbetween the plugs that connect the o2 sensor to the wire harness for the truck? Which sensor would I plug it into? THanks..learn something new everyday

You would remove your cat O2 sensor, replace with the sim, all the ones I have used were cut and splice

 

[porshapower]

Thanks again!! You have really made me understand this..

For the heck of it Im going to switch the o2 sensor they gave me "before the cat" and see what happens. If it trips Ill buy the one after the cat. If it trips again...Ill send them back and buy this "sim"...Thanks and Ill keep you posted!! Nelson

 

[porshapower]

Installed the 02 sensors

After installing the one on bank 1 before the cat..I reset computer and drove around to get the check engine light. Bought the one after the catalytic converter and installed that one and reset the computer. Drove around for about 3 hours and no check engine light. Only thing is my truck stinks! The exhaust smells like the exhaust on my old 57 chevy. Is this because of no catalytic converter? THanksNel