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Oxygen sensor VS A/F sensor? Urgent help needed!

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Old Aug 23, 2010 | 12:49 PM
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Exclamation Oxygen sensor VS A/F sensor? Urgent help needed!

So I'm in the middle of installing my headers and of course the factory sensors strip the thread when you remove them from the headers.

I need to order the correct part but I'm receiving conflicting information on what to order.

The factory part says: Toyota 89467-53020 and its made by denso
One place says I need the denso 234-9051 (some sites call it 02 sensor others call it an A/F sensor) but on denso's site it doesn't list it as compatible under the cross reference section and it looks different in the picture than the part I have.

When I search Denso's site it tells me I need part 234-9048 which the picture does look like the sensor I removed but I can't find anyone that sells that part number?

Every time I search the toyota part number I get refered to walker products W0133-1894301 oxygen sensor.

What the heck am I supposed to order?!?!?!?

here are pics to help show what im talking about

This is the sensor it tells me are compatible:
this one has a short cable like the front one and the grey part that plugs in matches so maybe its right even though the sensor tip looks different? Denso part# 234-9051 the problem is some sites list this as the REAR sensor how could it be rear when the cable is so short and doesnt have the gasket or the metal cup?

This is another one but this one looks like the rear since it has the longer cable and the cup around it: Denso part# 234-4521

This is what denso's site tells me I need and it looks exactly like the one I pulled off but nobody seems to sell it and i cant find any cross reference numbers? Denso part# 234-9048

Last edited by infinus; Aug 23, 2010 at 12:59 PM.
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Old Aug 23, 2010 | 01:05 PM
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I would save yourself the trouble and order your parts from a dealer... then you'll be sure to get the right parts. Many places call A/F sensors and O2 sensors the same thing, but they are two entirely different parts. The front sensors are AF sensors. The rear sensors are O2 sensors. They work differently... so id recommend ordering from Toyota/Lexus...
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Old Aug 23, 2010 | 01:51 PM
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The dealership wants twice the price of what other places charge and it will take 3-4 days to get here, I need them by tonight/tomorrow. Toyota told me its a lexus only part and none of the lexus dealers I called have em.

I ordered the first one, its listed as an A/F sensor at worldpac and the grey plug that goes to the car matches so I'm taking my chances with that because the rear 02 sensor has a different plug.
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Old Aug 23, 2010 | 02:09 PM
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One of the sensors arrived it looks to be a perfect match other than the length of the cable and the tip of the sensor which vary slightly, I guess I wont know till the 2nd one arrives from california tomorrow, we put it all back together and fire it up to go for a drive.
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Old Aug 23, 2010 | 02:21 PM
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The shape of the tip plays a role in how well the sensor works. I dont, however, know if the shape of the tip defines it as either an AF or O2... You will know as soon as you install it if it is the correct sensor or not.. Hopefully you got the correct sensors..
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Old Aug 23, 2010 | 03:06 PM
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Originally Posted by RTIS250
The shape of the tip plays a role in how well the sensor works. I dont, however, know if the shape of the tip defines it as either an AF or O2... You will know as soon as you install it if it is the correct sensor or not.. Hopefully you got the correct sensors..
The box specifically says air/fuel on it so im crossing my fingers.

I'll have to wait for the 2nd sensor to arrive tomorrow and install.

The headers come with a microprocessor to install to prevent it from throwing CEL's due to no cat's if they are the wrong ones is there any other way to tell other than a CEL? I imagine performance would be significantly reduced if they are the wrong ones as the car should go into some sort of limp mode if it is not getting the data it needs correct?
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Old Aug 23, 2010 | 04:52 PM
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The "microprocessor" it basically there to fake the rear O2 sensor reading.. With a working cat, the reading on the rear O2's will stay pretty flat, while with no cat, the readings will fluctuate up and down in a wave pattern. So the "chip" you install basically fakes the rear readings to the ECU. If the front sensors are incorrect, you will get a CEL pretty much immediately. O2 sensors work on a 0 to 1 volt scale (staying mostly .1-.9v), while AF sensors work on a 0 to 5 volt scale (staying mostly 2-4.5v). AF sensors also work on a current pumping principle. The numbers alone will set a code pretty much right away, so yea, if its wrong, you'lll know.
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Old Aug 23, 2010 | 05:18 PM
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Originally Posted by RTIS250
The "microprocessor" it basically there to fake the rear O2 sensor reading.. With a working cat, the reading on the rear O2's will stay pretty flat, while with no cat, the readings will fluctuate up and down in a wave pattern. So the "chip" you install basically fakes the rear readings to the ECU. If the front sensors are incorrect, you will get a CEL pretty much immediately. O2 sensors work on a 0 to 1 volt scale (staying mostly .1-.9v), while AF sensors work on a 0 to 5 volt scale (staying mostly 2-4.5v). AF sensors also work on a current pumping principle. The numbers alone will set a code pretty much right away, so yea, if its wrong, you'lll know.
Ok thats good to know. I'll report my findings back tomorrow after everything is all put together. Thanks for all your help!
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Old Aug 24, 2010 | 11:39 PM
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The second sensor arrived for the other side and even though the tip's were different it works flawlessly, no CEL's the only problem I ran into is that it was slightly shorter and I had to lengthen the wires for the passenger side sensor so it could reach the plug. It was denso part number 234-9051 and it is indeed an air/fuel sensor despite what other sites say.

Thanks for the helpful information!
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