Corolla O2 sensor question

[McManCSU]

My Corolla's engine light was on, so I got it diagnosed and found that it is the O2 sensor that had went bad. I don't think they checked the down stream sensor, but they suggested replacing both; I decided I would try just the upstream for now to save some $$. Anyway, there were no noticeable problems with the car aside from the light being on.

I went to NAPA, got a new O2 sensor and installed it. After installing it, the car had troubles with jolting coming off a stop and when running at lower speeds. I did some research and determined that the sensor must be bad since all I did was replace the sensor. I replaced with a new one and STILL have the same problem. I am totally lost now... Could it be some problem with mismatched brands of O2 sensors reporting different things? This seems unlikely to me, but I am not a car expert by any means. Suggestions or ideas?

Thanks!

[Airjer_]

What code specifically was present when you had it scanned. Was it a lean or rich code? If it was than I would check the MAF sensor for the build up of dirt/debris. If its dirty clean it with some MAF cleaner and see if it helps.

[McManCSU]

One more thing. I noticed that the resistance on the 4 pin connector measured around 10 ohms across two pins, but was open on the other two pins. Without needing specific readings, shouldn't there be SOME resistance between each set of pins? I have to check if the same pins are measuring as an open circuit on the old and the new I guess.

[quick69gto]

I suggest starting over again.
Install the old O2 sensor, clear all codes from the computer, drive it until the check engine light comes back on.
Once the check engine light comes back on, use a scanner to check the codes. The scanner will tell you if it's O2 sensor bank 1 or O2 sensor bank 2.
Bank 1 = at the engine (usually in the exhaust manifold)
Bank 2 = down stream of the catalytic converter

If the scanner says both are bad, then replace both O2 sensors.

Good luck!

[Airjer_]

Originally Posted by quick69gto

I suggest starting over again.
Install the old O2 sensor, clear all codes from the computer, drive it until the check engine light comes back on.
Once the check engine light comes back on, use a scanner to check the codes. The scanner will tell you if it's O2 sensor bank 1 or O2 sensor bank 2.
Bank 1 = at the engine (usually in the exhaust manifold)
Bank 2 = down stream of the catalytic converter

If the scanner says both are bad, then replace both O2 sensors.

Good luck!

This would be a four cylinder and would not have a bank 2. Bank one would be the only option. If it where a v-6 than it would have a bank 2 (the opposite side of the engine from bank one which is the side of the engine with the number one cylinder). There are two sensors on bank 1, which are bank 1 sensor 1, and bank 1 sensor 2. Sensor 1 is upstream of the cat, sensor 2 is downstream of the cat.

I know its nitpicky but terminology can make a huge difference in what you fix and how much it will cost!!

Its not real common for both O2 to go bad at the same time. One can go bad (and they do) but they rarely cause drivability problems unless there stuck extreme rich or lean.

[quick69gto]

Crap! You're right.
What the hell was I thinking?
I guess it's because I was diagnosing a 2000 Sienna late Friday and I'm still thinking about it.
Correction: Airjer is right. Bank 1, Sensor 1 or Sensor 2.

[Airjer_]

These guys know I have plenty of brain farts and typing before thinking on here. Its no big deal as long as the right info gets out in the end!!

[NotoriousPhil]

Be aware that an O2 sensor code is almost never because the o2 sensor has to be changed. Most likely causes are misfires and defective MAF sensor as was previously stated. If you can find out if the code is on because it is rich or lean would help you to find out why.