How many o2 sensors are there?

I was just wondering how many o2 sensors are on our truck. I went to advanced auto(will never go back again). They finally came to the conclusion that it was the upstream o2 sensor. I bought it because i know for a fact it is(Ive gone to orielly and autozone and got the same code but they told me it was o2 sensor)

There are two catalytic converters...I see one after the second one and another inbetween them but cant tell if there is one on the headers or inside the engine bay.

 

There are 2. That's unfortunate you didn't like advance auto, they always have good prices and online coupons. I save tons through them.

 

Yeah i guess since im a teenager i get treated different. My dad prefers them over autozone but i will never go back there!

And thanks for the help! Going to replace it now!

 

I can second the motion on advance auto by isu2014, I just had to do both o2 sensors on my Tacoma to pass NYS inspection, and they had the parts at a discount on line. I picked up the parts at the local store and was on my way in no time. Too bad your experience was negative.

 

Advance recognizes the upstream o2 sensor as the air/ fuel ratio sensor and the downstream is recognized as an o2 sensor. When I was looking for the part the guy couldn't find the upstream because he was using O2 sensor as the "key word search".

 

This is correct. Only have 1 02 sensor (after the cats) and 1 AFR sensor (before the cats).

 

Where exactly the AFR sensor located at? I just change my 2 converter and the 02 sensor but my check engine light came on 2 day afterwards. I used the scanner it said Air Fuel Sensor. I notsure are there 2 different sensor? Or just the 02 sensor.

 

I don't see any info on your truck. If you have a 2.7l 4 cyl, the a/f sensor is between the exhaust manifold and the first cat, on the exhaust pipe as it heads down to the cat. The connection plug is along side the transmission on the passenger side.