What does "Undo 1/2 a turn spray the threads and thread back 1/4 turn." mean?

I am guessing that means make a 1/2 (anti-clock-wise) turn, spray (W4, liquid wrench?) into the thread and turn back 1/4 turn (clock-wise), and then keep turning the sensor loose.

Thank you.

 

After you break the sensor loose it may bind. Spray the base area with a penetrant and turn the sensor in a clockwise direction. Back it off and if it starts to seize spray it again and tighten a little and keep repeating until you have the sensor removed. If you continue to force the removal you can gall the threads and end up with stripped threads in the mounting bung. Not a good situation.
Be patient and work the sensor back and forth if difficult to remove to keep from destroying the threads on the mounting bung.

 

Bad news - it did not work out after about an hour with it.

I started on Friday evening with the car parked in the garage and deposited/socked some W4 between the sensor and it's seat, with an old sock beneath the sensor to catch any runover. I continued with W4 on Saturday every 3-4 hours and until early afternnon on Sunday.

On Sunday afternoon I removed the relay box and it's mounting bracket, inserted the sensor socket onto the sensor bottum and tightened the adjustable clamp on the socket. I then inserted the wrench in to the socket and tried to turn the sensor loose with the help of a 15" gas pipe. But I cannot get the sensor to move, primarily because there seems not enough wiggle room for the wrench get the full pull.

The socket is a 22mm one. It doesn't seems to fit the sensor tight enough - there are some wiggle room between the sensor bottum and the 22mm socket. Am I not using the right sensor? This is the only oxygen sensor socket set at my local AutoZone store and they said that it is the right one to use.

For some reason unknown to me, the "Check Engine" light now is off.

I am pushing taking the vehicle to the local Toyota dealership back for a week or two, before I exhaust all my options - get a tightly fit socket, for example.

 

I would phrase is as "not good news". Bad news would if something broke.

You can test out the socket with the new sensor and even measure the face with a caliper.

If you want to pursue further try a better penetrating oil like PBBlaseter or Liquid wrench. You may even try the propane torch.

Salim

 

Finally, the A/F sensor is off its seat!
I started this past Friday evening, by socking the seat with drips of Rust Eater - Penetrating Spray (from my local AutoZone store) every couple of hours. On Saturday, I used the 22mm socket (the long one in the three-piece set, which seems to have less gap with the sensor bottum), an adjustable band clamp, a 15" wrench and a 18" section of gas pipe and managed to move the sensor for about 3-5 degree. Then it stuck. For the rest of the day, I keep moving the sensor (every couple hours, when ever I had the chance to do it) on both directions while dripping the Rust Eater into the tiny space between the sensor bottum and its seat. This continued through Sunday until Monday afternoon (Labor Day break here), when I felt "enough is enough" and put more force to the wrench and the pipe. It moved more and I kept turning the sensor in both directions with drips of the Rust Eater until it was obviouse that the sensor was ready to come off. Finaly it did come off.

I examined the threads on the sensor and one section of one turn is some what damaged. I used flash light and looked the threads on the seat and I can see some raw steel on a small section of one turn and there is a small section (about 2mm) of the teeth on another turn is missing.

I think the seat needs to be rethreaded. What tools and what size do I need to do this thread repair job? (The booklet in the new sensor's packing box doesn't have the thread measures listed.)

What puzzles me is that the threads on the sensor and its seat don't show any rust at all - they are mostly in black and small sections show raw steel. What caused the sensor stuck in its seat?

Thank you all for the suggestions that guided me getting this sensor off its seat.

 

You have 2 different metal pieces, which have gone trough heat cycles. Make sure you coat the threads with the anti-sieze compound.

Salim

 

Got a 18mm Spark plug thread chaser (just a little over $7) at a local NAPA store, where I was told that all oxygen sensors have 18mm threads; took about 30-minutes to work the seat thread slowly with constant application of lubs, by turning the chaser back and forth with an adjustable wrench; had about 6 turns of the chaser into the seat and that was enough for me (the sensor has about 4 turns of threads).

The rest is simple: wipped a thin coat of the anti-freez gel (came with the sensor package) just so that all threads in the seat and on the sensor are covered; used hand turning the sensor into the seat until all threads are in and then used a 22mm open-end wrench to tighten it.

Reset the CEL by disenaging the fuse (shown in the DIY post) for 3-5 seconds and then push the fuse in again; insert the connector into the socket; reinstall the relay box mounting bracket and put the box back on; collect the tools and everything from the engine compartment; start the engine and the CEL light is off in a second. The vehicle runs great.

A happy ending - thank you for all the advice.

 

Now tell us how good a fit was 7/8" tool instead of 22mm (size of the sensor).

I generally refrain from using adjustable and even open end wrench(es). I always reach for my trusty torque wrench to finish a job.

Salim

 

The three-piece oxygen sensor socket set (OEM 27110) I got from local AutoZone store as a loaner unit doesn't not fit the A/F sensor 234-9009 tight enough. All three pieces leave 2-3mm side gap, with the long socket with the smallest gap. I used this long socket to get enough turning radius - just barely one-click in the rachet that allowed me to turn the sensor loose slowly.

I used the adjustable wrench for most part while installing the new sensor, as there is almost no resistance in the early part after the seat threads were repaired. I used a 22mm open-end wrench for the final couple of turns at the end.

My order of a new OEM27110 oxygen sensor socket set came in last Friday from Amarzon.com. (I need my own set for more A/F and oxygent sensors replacement jobs on the two RX300s in the house.) All three pieces in this new set fits the new sensor very tight and doesn't leave any gap. So I guess the AutoZone loaner set was not used cauciousely (e.g., with an adjustable band clapm) and forced the openning to get wider and wider in every use and by the time when I got the lonaer set it was about 2mm in gap. My new set has the exact same codes stampted on each piece as the AutoZone loaner set but all three fit a new Denso 234-9009 A/F sensor very tight.

Unlike a traditional tap-die tool, the 18mm spark plug/oxygen sensor thread chaser doesn't cut any metal off, so it is very hard to work it. I worked it slowly, making a half-turn in and 1/4 turn out with W4 spray drips. It took me about a half hour to get 6 turns of the thread chaser into the seat. After that, installing the new sensor is easy (did have the supplied anti-freez covering all the threads in the seat and on the sensor) - just make sure that the wire cord is turning with the sensor while installing it and the cord is secured after the connector is inserted into the socket.