How Many Oxygen Sensors Are There?

[pabs]

I recently replaced one of the oxygen sensors because the engine light came on. one day later it came back and now the mechanic says its another oxygen sensor and that there are 4 of them and usually when you replace one the others soon start to fail as well. If someone can give me some insight on this topic, it would be helpful. thanks

[mburnickas]

I recently replaced one of the oxygen sensors because the engine light came on. one day later it came back and now the mechanic says its another oxygen sensor and that there are 4 of them and usually when you replace one the others soon start to fail as well. If someone can give me some insight on this topic, it would be helpful. thanks

You replaced the one the DTC says too. I would not agree with the once one goes deal.

[Lexusfreak]

What year is your ES?

[pabs]

Yes, I replaced the one that the computer was bringing up, and now the one near the radiator is bad according to him. I have a 1999 es300 sorry for not mentioning that in my earlier post.

[Lexusfreak]

This is what I got from the NGK website...

Oxygen Sensor Part No. Location Note Photo

Oxygen Sensor 24656 Upstream Left n/a

Oxygen Sensor 24656 Upstream Right n/a

Oxygen Sensor 24566 Downstream n/a

It states only 3 sensors, not 4.....can anyone confirm?

[gordonw]

For a 1999, only three.

[pabs]

thanks to everyone.

[pabs]

is the consenus that when one fails most of the time the others don't, or is the mechanic right that they start failing after one another

[Ratatat]

like most o2 systems, the upstream 02's tell the computer how the engine is running, while the downstream one tells the computer if the converter is working or not.

[mburnickas]

You can use a OBDII/CAN reader and see the readings on the O2 sensors and see what they are doing. OR check the readings with a meter. A clean burning engine will make them last longer.