First.. The car: 2000 Camry CE - Automatic 4cl (Not Calif.)

I replaced the FRONT O2 sensor with a DENSO (PN: 234-4209)

I bought this sensor for 3 reasons, 1. Advanced Auto said it was the right part, 2. The Denso site said it was the right part and 3. the OEM in the camry was also a DENSO.

The only difference between this O2 sensor and the original one is that this one is a universal.

I had no problem matching up the wires, they were identical on the new O2 sensor and the old. And I followed the directions to the letter.

So at this point everything is well.

I cleared the error codes from the car and have driven it 200+ miles and the engine light has remained off.

But, when I am stopped at a stoplight the idle is bouncing between the 2nd and 3rd click on the tachometer. (I think the 3rd click is the normal idle mark).

And when I step on the gas to go, the car hesitates.. in sort of a jerky way. It's quite a ride being jerked back and forth.

Now, if I disconnect the O2 sensor and drive, everything is normal, it rides sooth as silk (but the engine light will eventually come back on with no O2 Sensor).

I have tested the car again with the OBDII Scanner to see if there are any underlying codes that may be there even though the engine light is off, and it passed. The screen read "PASSED No Codes To Read"

So I am puzzled as to what may be the problem.

If anyone can think of something that I missed, I just don't know or has had a similar problem and found a solution, please share.

 

If its the upstream sensor (ahead of the catalyst), you have an Air/Fuel ratio sensor up there and NOT an O2 sensor. They are NOT interchangable. Go to the dealer and buy the correct part.

JJ

 

Wow! You are 100% right. I did some reading on the subject and I'll share what I learned and what you said, but I'll add a little detail.

First Joel_CA is 100% correct, there is a big difference between an O2 Sensor and a A/F Sensor. And although they look identical, they are not. And again Joel was correct in saying that they are not interchangeable.

See, in the Camry models from the year 2000 and up, Toyota decided that they needed to improve on the fuel system and said "Hey.. Lets change out the O2 Sensors that we used to use with Air/Fuel Sensors instead".

The difference between an O2 Sensor and a A/F Sensor is pretty easy to explain. Basically an O2 sensor sends data back to the computer in pulses or chunks. It gets a reading, sends the data, resets itself, gets another reading and sends it, and so on. This is why my idle was going up and down.

The Air/Fuel Sensor does basicly the same thing the O2 Sensor does, but the only difference is, that the A/F Sensor doesn't break up, pulse or send the data in chunks, it keeps the data flowing and provides a constant supply of data.

So my front sensor that I replaced with an O2 Sensor instead of a A/F sent data, the rear O2 Sensor read that data and said "Everything's OK regulate that EGR Valve... Whoops!! No Data!! QUICK! Fix It! Whoops!! Now There's Data Again!! Everything's OK, whoops, no it's not! Yes it is! No it's not!"

There. That was my idiots guide to O2 vs. A/F Sensors.
I hope it was educational and funny.

 

Very funny- but incorrect, therefore not educational

JJ