need help what sensor for code p0133

[PSHUMARD1]

Hello all like the subject says I searched and know its rear primary bank 1 sensor 1 but some of the site I looked at to buy says upstream or downstream so not sure which to buy. Part #would be great id like to stay with as close to OEM as possible. Thanks

 

[N-Wing]

I would go to www.oxygensensors.com. Or call 877-384-8444. Bank 1 sensor 1 is the rear side bank like you said and its the first sensor of the two from the Engine as I recall. Mine code was P0135. I don't have a code list though. They were very helpful on the phone. I bought the Denso which was Item 234-4730 although I'm not sure that is the part number.