Rxlexus350

Hi,

I replaced two of the sensors under the car of my 2010 rx350.

My mechanic showed me another o2 sensor under the hood. Here’s a pic, is that also another o2 sensor???

thx

Mesquite77

No, that is an Air Fuel sensor, or A/F Sensor. Which looks exactly the same as an O2 sensor. Before each bank's cat is an A/F sensor, to determine air fuel ratio mixture, via ECU to injectors, and after each banks cat is an O2 sensor, which monitors the efficiency of the cats. I've seen some posts that suggest the O2 readings also contribute to air fuel mixture, but can't confirm, that is up to the A/F sensors AFIK.

Rxlexus350

So the pic shows an a/f sensor, correct?

Rxlexus350

And is there one or two under the hood?

Mesquite77

>>> Before each bank's cat is an A/F sensor, to determine air fuel ratio mixture, via ECU to injectors, and after each banks cat is an O2 sensor

Your V6 has 2 banks, each bank has an A/F sensor at the exhaust port manifold, at top of engine, and each has an O2 sensor after the cat on bottom of car.

The bank cats are part of the exhaust manifold, there may be a third cat under the car after the Y join of the exhaust, but there is not a fifth sensor for that one, only California knows why it is even there.

So 2 A/F sensors and 2 O2 sensors, your pic is of the bank 2 (radiator side) A/F sensor. Don't replace it unless engine is not running correctly and you have fuel trim, DTC code issues.

Rxlexus350

I have VSC, Check Engine and AWD lights on. And a few people recommended to start with the sensors. The code that I get is in the pic-

Mesquite77

Head over to 2nd gen forum, same 2gr-fe RX350 engines, but older and more help on issues. I.e.: https://www.clublexus.com/forums/rx-...n-sensors.html

Bank 1 is firewall side, you may have a bad cat, but read through the threads. I would not change the A/F sensors for this, proper diagnostics needed.

Rxlexus350

Great thanks! Will check out the other thread.