Yesterday I replaced the rear A/F Sensor on my 2000 RX-300 with the help of everyone who has submitted excellent info to the forum. The job looked quite intimidating but I dove in and accomplished the job.
At first I was having a difficult time removing the connector. From the bottom side I could wiggle the connector but could not keep the latch depressed. After several attempts I was able to separate the plug a little ways and put tension on the latch, then when I depressed the latch, again, I heard a click. Then it was a matter of working the connector out. An open end wrench and a few heavy taps with a dead blow hammer and I was in tall cotton.
I would like to thank everyone who has contributed to the forum for all the information provided.

Bearbrew

 

That's great to hear.

I'd like to do mine soon as preventative maintenance. I still have my original A/F sensors, but I know the years in Mexico took their toll on them. I saw them for $113 each or so on Amazon (Denso).

 

That's what I would call an unbeatable price! I wouldn't want to chance anything but Denso.

 

Just checked Amazon and the price is still $113.00 and change. When I bought mine last month the price was $126.00 and change. Must be time to buy them if you are planning on changing them in the near future.
The front sensor connector is a lot easier to disconnect if you remove the air filter box IMHO.

 

I was trying to replace the front A/F sensor this afternoon. I checked out the sensor remove/install socket set from local AutoZone. I was able to disengage the connector after a few tries. But now the problem is with removing the sensor from its seat - it just wouldn't move. Bearbrew mentioned "a few heavy taps with a dead blow hammer" to loosen up the sensor. I guess this was done several times and at different sides. With the front one, the only way to access the sensor is from the top - would "heavy taps with a dead blow hammer" at one side of the sensor work?

Any other things that one can do to loosening up the sensor from its seat?

By the way, I purchased the Denso A/F sensor (234-9009) on Amarzon last week and it was $100 plus change and free shipping.

 

chenxingha,

Did you spray any type of a pentrant, such as Sea Foam, Kroil or Knock er Loose at the mating surface an hour or so before you attempted to remove the sensor? Any of the good penetrating fluids will help as long as the sensor isn't seized in place.

A last resort, if the sensor is frozen in place, is to cut off the bung on the manifold and have a new one welded in place. But that is a last resort.

It looks like the price of the sensor just keeps coming down. They must be selling a lot of them.

Bear

 

Heat it up with a torch or hit it with an impact wrench, the electric impact wrenches are great for this type of thing.

 

I had tried all the different things but was not able to remove the sensor behind the radiator. Went to an independent mechanic and he was also not able to open it with one wrench.
Then he used 2 wrenches, closed end of the first one put at the sensor, and the open end of this wrench he hooked to the second strong wrench..... and the sensor came out with very little effort....

So essentially what we need is extra torque, unless the sensor is really frozen into manifold. Either get the largest closed end wrench that you can find. Or use 2 wrenches to join them and get that extra torque.

 

Makes you wonder how much torque was used during assembly. Then again, heat, road salts and anything else present can make some items very difficult to remove.

Bearbrew

 

I acturally U-bolted a 2-feet-long 3/4 gas pipe with a 22mm close-end wrench and tried it on the sensor, which did not move a bit. I did not use any chemical loosener/spray, being afriad for any residu may cause fire in the engine compartment - it is wife's car.

Torch the seat off can get the sensor off but I am not sure the tight space would allow anyone to seal a new seat thoroughly - there is no way to get the torch to the bottum side. Although I don't own a impact gun, I don't see how to get the tool in there - I can hardly even to form a fist with my hands in that tight area.

I called my local Toyota dealer today (my area doesn't have a Lexus shop) and they checked with their shop technician - they are willing to give it a try for $120 + NY tax.

I continue to collect suggestions until this weekend and give it my best effort - heat the seat, etc. If I am still unable to get this sensor to move, it will be in the dealer lot on Monday.

Thank you all.

 

Borrowed from other threads.

 

If you can get something like this it makes life a whole lot easier. Came loose in seconds with a bit of force.

http://www.machinemart.co.uk/shop/pr...-socket-wrench

 

I would even put an adjustable band clamp [the one that goes over hoses] on the split socket. This will prevent any tendency of the split to open up under force.

Salim

 

Thanks for the pictures - I was wondering what goes with the bigger socket. Moving the fuse box out of the way is a very good idea - why haven't I thought about it! Using a band clamp is also a good idea.

I have a 15"-long wrench that goes into the bigger socket. I will go to HomeDepot to cut a 2-feet long 1" gas pipe (to help with the wrench), a band clamp that goes onto the bigger socket and a torch.

Looks like I am going to have a fun and exciting weekend with these tools.

 

One more bit of free advice ..
Undo 1/2 a turn spray the threads and thread back 1/4 turn.

With enough leverage, you will be able to budge the thing, but there is a slight risk. I hear shops are now passing on the risk to customers ... cost if every thing goes fine and a higher price if things go bad.

Also remember to put the anti-seize grease, when installing the new sensor.

Salim