Hello,

I have a 1994 Lexus ES300. The engine light recently came on. I took it to Auto Zone for a test (OBD2 test?). Turns out I have an Oxygen Sensor out. It's the "Bank 1 Sensor 1" sensor.

Questions:

Is the "Bank 1 Sensor 1" O2 Sensor the one that's at the front of the car? Or is it one of the others?

Is it the "upstream" or "downstream" sensor (I noticed on Ebay there's the 2 different ones)

Where's the best place to buy these sensors? Ebay has them for around 20 to 30 bucks..

Thank you

 

That should be the up stream one, bank 2 would be the downstream.

 

Bank 1 Sensor 1 is the one on the right side of the engine which is closest to the rear of the car.

Bank 2 Sensor 1 is on the left side of the engine. That's the one at the front of the car.

Sensor 1 refers to an upstream sensor.

Buy Denso O2 sensors. I buy mine from Amazon. The one you need sells for about $48.

 

'Bank' refers to the side (or bank) of the engine.

Up stream or down stream refers to the order of appearance in relation to flow.

Therefore Bank 1 Sensor 1 would be on the left side of the engine, the first sensor.

 

^^^ I stand Corrected.

 

The best way to see exactly where that sensor is is to climb a bit into the bay from the drivers side, looking behind the engine, against the firewall towards the passenger side. You'll see the O2 sensor sticking out with it's attached cable. Yes, it appears to be a pain in the butt to get to.

Buy only Denso or OEM sensors. If you happen to have california spec vehicle, you might need Air Fuel ratio sensors and not 02 sensors. Check that.

 

This is wrong. Bank 1 Sensor 1 is on the right side of the engine, the bank nearest the rear of the car. Remember the engine is turned 90 degrees in the engine compartment with the front of the engine on the passengers side of the car.

Edit: This presumes the driver's side is on left side of the car. Thanks to 80ES300 for pointing out the geographical location can cause confusion due to different driver's position.

 

He has a 1994 model. His model only has O2 sensors. No Air fuel ratio sensors in this model year.

 

Tom,

Do you happen to know the part #? I have an Amazon Prime membership, so I'll definitely buy it there… Just want to make sure I buy the correct one…

Thanks Tom

 

On Denso website, it says 234-4622 for 94 es300 but double check.

Tom,
Looks like ES300_NZ is in New Zealand and hence the left/right side confusion. Its best to say that sensor 1 is near the firewall side or as you said side of the engine closer to the rear of the car

 

That does appear to be the one I want on the Denso website… As long as we're sure I want the "Upstream" sensor..

 

Figures… That's the one sensor that isn't Amazon "Prime"…

 

I assume the engine is still turned 90 degrees with the front of the engine on the right side of the car. Irregardless, bank 1 is on the right side of the engine regardless of its orientation in the engine compartment.

BTW, I added a clarifying edit to my previous post because, as you pointed out, my description would be inaccurate if the driver's side is on the right. Thanks.

 

It shows up as prime for me.
Yes you want the upstream sensor. Denso 234-4622 Oxygen Sensor

 

I was still wrong, I assumed the front was the left. Taking left from standing at the crank and going left/right from there. This happens, .. I've been known to be wrong every decade or so my wife tells me.