02 sensor Air fuel sensor help

sorry i know alot of these posts have been made but the more i look at them the more confused i get, i recently have had a check engine light come on for my 2000 tacoma v6 (manual) code was P0420 friend sent a chart and said it could be A/F sensor (bank 1 sensor 1) Heated oxygen sensor (bank 1 sensor 2) or my cat, i figured i would start with my sensors but like i said the more i try to look those 2 up i get confused on how many and what one to buy some people say i need a air fuel sensor or just 2 02 sensors, i thought i had the part number for them but when i went to purchase on Amazon it said it would not fit my truck, so can anyone please help link me those 2 parts for my truck please? sorry if i left something out

 

Now the PO420 Code just says what ever the difference is between your Front and Rear Sensors The ECM is not seeing enough of a change

This can be from a leaking exhaust gasket

A bad most often rear sensor

A Bad Cat

Wiring from the Sensor To the ECM or the ECM

Now do you know Just what Emissions package you have Tacoma`s with the California package are all over the country !!

Now if you have the California Emissions The front one (upstream) is A Air Fuel Sensor Denso #

$170 234-9003 Air Fuel Ratio Sensor

234-9003

The rear ( Down Stream) is

$61 Denso 234-4189 Oxygen Sensor

Denso 234-4189 O2 Sensor

Only the California Emissions Package has the Air Fuel Sensor upstream

This is other then California Below

If you have the Federal Package Front (upstream) Denso #

$53 234-4161 Oxygen Sensor with 15.35” 4-Wire Harness

234-4161

Rear (downstream) Denso #

$53 234-4154 Toyota 4WD Truck Downstream Oxygen Sensor with 12.9” 4-Wire Harness

234-4154

If I recall the only difference between these two is the length of the pig tail on the Sensor

Hope this helps

 

how do i find out what package i have? i did purchase this in California and am currently living there also does that mean i need #

$170 234-9003 Air Fuel Ratio Sensor

234-9003 for my a/f sensor (upstream) and

$61 234-4189 Oxygen Sensor

234-4189 O2 Sensor (for downstream) and thank you for quick response

 

Pretty easy to tell Living where you do

California will have two cats

Yes then you would need the Sensors you have listed above .

 

i wish i could remember as iv only been under the truck for oil change and taking off the driveline to take in to replace the u-joint, thank you so much for quick response i will look tomorrow as it is 3:40 am atm >.> i will look tommorow and thank you so much for quick responses!!! you are a god amongst men

 

ok now im back i took pictures of both these are they both cats? the smaller one is closer towards my passenger tire and the longer one is futher back... and beyond that there is the big muffler so does that mean these two are both cats?, sorry i cant even find this in my manual

 

Looks like you have two catalytic converters.

 

sweet thank you for quick response ! i kno what to order now woot!

 

The rear cat on yours is either an aftermarket cat or it's just missing the heat shield.

 

The heat shields rusted off

Even Aftermarket cats come with heat shields

 

as far as i know everything was stock(except the grey wire mod) when i purchased this from a friend of a friend and it sounds completely stock ,very quiet indeed compared to my other friends who own aftermarket exhausts, and i want to thank you both for replying back so quickly this was a good introduction to this forum and i will be back for sure

 

Glad we have your issue figured out

 

It’s a missing heat shield