2003 Toyota Avalon A/F Sensor Replacement

[Maui]

I have a 2003 Toyota Avalon, and earlier this year the idiot lights on the dash lit up. So I downloaded the code and discovered that my Bank 1 Sensor 2 code had tripped, meaning that one of my upstream Air/Fuel Oxygen Sensors needed to be replaced. Since it has a built-in heater, they are quite expensive. I found a Denso brand replacement sensor online and ordered it. Replacing the existing sensor was a piece of cake. Pop the hood and there it is right in front of you. A 7/8" box end wrench was all I needed. The old sensor came right out after a little effort was needed to break it free, and I had the entire repair completed in about 15 minutes. Now the code for Bank 1 Sensor 1 has tripped, meaning that the second upstream A/F sensor needs to be replaced. This one is on the backside of the engine, is lower, and is a bear to reach. And it will NOT break free! I've wire brushed the exposed threads to remove as much of the rust/**** as possible, and I've been spraying it with different types of penetrating oils for over three weeks now. It simply won't budge. I am open to recommendations from the group here. Any suggestions? And before anybody here even brings it up, no, you cannot get a torch in there.

 

[Rinspeed]

Can you cut the wires and get a socket on it.

 

[rooster59]

autozone, or like stores may have ⅞ O2 sensor socket, maybe free loaner. I’ve had good luck with the offset ones and use a breaker bar.

 

[tooljunkie4]

Take the car for a drive. Get the engine nice and hot. A 6-point box wrench (7/8" or 22 mm) and a hammer work well together on these.

I like this hammer for the task:



An alternative would be to remove the entire manifold, and either torch or drill out the sensor while the whole system is locked in your vise.

 

[3baygarage]

Would one of those induction tools do the trick?

 

[Maui]

Can you cut the wires and get a socket on it.

I can. But I haven’t done that yet because this is my main driver, and I needed to drive the car on some relatively long trips over the past several weeks. I have noticed that the car does run smoother if the sensor is connected. Only the heating element has gone bad. The rest of the sensor still appears to work. But the car won’t pass inspection with the idiot lights lit up. And the inspection is due by the end of the month. After I drive home tomorrow I won’t have any more long trips planned for about 10 days. So if I have to yes, I can cut the wires off and get a 6 point socket on it. And I can position the breaker bar so I can get a pipe over it. My fear is that I will shear the sensor off with the threads still stuck in place. I have sheared bolt heads off on engine blocks before, and this would be bad if I did that here. Really bad.

 

[Maui]

Take the car for a drive. Get the engine nice and hot. A 6-point box wrench (7/8" or 22 mm) and a hammer work well together on these.

I like this hammer for the task:



An alternative would be to remove the entire manifold, and either torch or drill out the sensor while the whole system is locked in your vise.

I understand what you are saying, but the sensor is on the back of the engine. It is NOT in a place where you can put a wrench on the sensor and whack the wrench.

 

[Maui]

To continue my post, this thing is buried on the back of the engine, not on the very bottom of it. I can get a wrench on it, but there really isn’t a simple way to hit the wrench directly with a hammer. There simply isn’t enough room. I can place an aluminum rod in contact with the wrench and then hit the rod. Or I can cut the wires, use a six point socket and breaker bar, slide a pipe over the breaker bar handle, and then hit the pipe with a hammer.

 

[j3rf]

Sensor 1 is your upstream, sensor 2 is your downstream in case you were curious.

 

[Maui]

According to the guys I spoke with at the toyota dealership they are both upstream sensors. One sensor handles 3 of the cylinders, and the other sensor handles the other 3 cylinders.

 

[Maui]

autozone, or like stores may have ⅞ O2 sensor socket, maybe free loaner. I’ve had good luck with the offset ones and use a breaker bar.

Thanks for letting me know. I have one right down the road from me, and will ask them about it. I have a breaker bar that I could attach to it.

 

[xjfish]

It will come out if you can get enough leverage. 7/8" or 22mm socket. Thread damage is a possibility. 02 Sensor thread taps are available to repair.

 

[tooljunkie4]

...because this is my main driver, and I needed to drive the car on some relatively long trips over the past several weeks. I have noticed that the car does run smoother if the sensor is connected. Only the heating element has gone bad. The rest of the sensor still appears to work. But the car won’t pass inspection with the idiot lights lit up. And the inspection is due by the end of the month. After I drive home tomorrow I won’t have any more long trips planned for about 10 days. So if I have to yes, I can cut the wires off and get a 6 point socket on it. And I can position the breaker bar so I can get a pipe over it. My fear is that I will shear the sensor off with the threads still stuck in place. I have sheared bolt heads off on engine blocks before, and this would be bad if I did that here. Really bad.

Where in NY are you? Perhaps one of us is in good position to help if needed. It can't hurt to have a backup plan.

 

[Maui]

Where in NY are you? Perhaps one of us is in good position to help if needed. It can't hurt to have a backup plan.

Good idea. I’m in the Rochester area in upstate New York.

 

[Jswain]

Deleted

 

[turner66]

The method I've used when I encounter a seized O2 sensor in a tight space when no other option works is to spray with your favorite penetrant, then (assuming you have air tools...) put your box end (or socket/breaker bar) on the sensor and then use an air hammer and pickle fork and put that over the wrench handle (slow hammer speed) and "shock" the wrench/sensor. It basically accomplishes the same thing as swinging a hammer without the need for the swing room... Good luck

 

[Maui]

The method I've used when I encounter a seized O2 sensor in a tight space when no other option works is to spray with your favorite penetrant, then (assuming you have air tools...) put your box end (or socket/breaker bar) on the sensor and then use an air hammer and pickle fork and put that over the wrench handle (slow hammer speed) and "shock" the wrench/sensor. It basically accomplishes the same thing as swinging a hammer without the need for the swing room... Good luck

I did see that in a Youtube video I found. The mechanic said it worked every time. If what I try next doesn't end up working, that will probably be my next plan of attack.

 

[bwringer]

I have a Craftsman 22mm combination wrench with a six point box end for these situations... I bought it at an actual Sears, so that should tell you something about how long ago it was. 22mm is a squidge tighter than 7/8".

Sometimes taking the car for a quick rip and going at it while the exhaust is blazing hot helps.

At some point, brute force only bends or breaks the exhaust, or strips out the threads, so it's important to not get frustrated and apply excessive muscle. Keep using vibration, unguents, heat, etc. until she gives way.

I also discovered the difference between an ordinary 02 sensor and Toyota's upstream AFR sensor a while back. We had a Camry that came to us with a fresh O2 sensor some shop had installed, but after while it started popping CELs; turns out there's some sort of different mojo happening with the original pointy-nosed Denso sensor, and the car isn't quite happy until you give it exactly what it expects.

 

[2ndGearRubber]

^ FWIW the sensors are 22mm, not 7/8. You always want to use a 22mm. IIRC 7/8 vacuum switches had their own special socket that looks like an O2 sensor socket, so even manufacturers list them incorrectly.


Also an A/F sensor is basically worthless without a heater circuit functioning, so it's not just the engine lamp you're fixing. The car will actually be in fuel control again on that bank.

 

[ItsNemo]

Heat....torch on the pipe around the threads until it's good and hot, will just turn right out. All the sprays and hitting and impacts and whatever else you can think of will not do nearly as much as getting the pipe hot (and not the sensor).

I've definitely also cut wires on sensors and brake hoses that are failed so I can get a regular deep socket on it rather than any sort of wrench.

 

[MBfreak]

Try my go-to rusted thread killer.
50 % acetone, 50 % ATF.

Works wonders for me.

Ola

 

[Maui]

If I cut the wires I can get a deep 6 point socket on it and I believe I have just enough room to attach this air ratchet to the socket. Since I can dial the air pressure to whatever value I like, I can gradually increase the applied torque as I see fit. So how does this sound? Liberally spray the threads with peneteating oil yet again, run the car to get it nice and warm, then put the socket and air ratchet in place, and actuate the ratchet in short bursts to shock the threads. Start out at about 30 psi pressure. If that doesn't do it (and it probably won't) and then increase the pressure to 40 psi and follow the same procedure all over again. Keep doing this by increasing the pressure in 10 psi steps until the sensor frees up. Is there something here that I am overlooking that can bite me?

 

[stonesfan68]

The air ratchet likely won’t have enough torque to get the job done.

 

[mike93lx]

Air ratchets are for running nuts/bolts down not for breaking stuff loose.

I bet it doesn't do anything regardless of pressure.

 

[redragoon]

There are also sockets available at HF, Northern Tool, and Amazon. I have one of the cheap sets. Worked on the sensors I swapped.

 

[JimH]

Are you sure that you are even on the right sensor?

 

[Maui]

Are you sure that you are even on the right sensor?

Yes, I am on the correct sensor. I already swapped out the other upstream sensor that cleared the code.

 

[Maui]

There are also sockets available at HF, Northern Tool, and Amazon. I have one of the cheap sets. Worked on the sensors I swapped.

I bought a set of those from Autozone the other day. The fit was sloppy with one of those offset sockets, and none of them worked to free up the stuck sensor. It was a no-go. I'm at the point now where I'm probably just going to go to a repair shop and have them take the damn thing out.

 

[signcrafter]

Heat is your friend with O2 sensors. Can you get a plumber's torch down in there?If not then brute force is your next best option. 6 point 22mm socket with breaker bar to get old out and can use your new O2 sensor socket to put new in without damaging wires.

Some pictures would help but if you can get a socket and breaker bar in there then I would think one of these torches would fit, https://www.amazon.com/dp/B08V5CW1KT/?tag=atomicindus08-20

 

[Rinspeed]

Not enough room to get a breaker bar in there, doubt the air ratchet will work.

 

[ctandc72]

This look the same?

Use the box end of a 22mm wrench on it, then hook the open end of another wrench onto the open end of the 22mm. That should let you manipulate the second wrench enough to get more room and get some leverage.

 

[APEowner]

The air ratchet isn't going to do anything except smash your hand against something from the reactive torque. Put your six point socket on there and the biggest ratchet or breaker bar you can fit and yank on it. If you think you need more than that then you might have a good excuse to buy an induction heater. I don't have a recomendation for a specific one. I fixed my rusty fastener problems by moving from NY to NM .

 

[strutaeng]

I've had good luck with the Lisle 12390 with breaker bar. Working under my trucks the 16-18" breaker 1/2" drive has worked for me. 24" breaker bar is usually too long. We don't really have to deal much with rust here, but O2s are still a pain to remove.

I also use the Lisle 12230 O2 sensor thread chaser.

I'm wondering how the dealership would access that sensor behind the engine? Have you tried looking for service data for any guidance? I'm not sure if that would have any information on the procedure, just thinking out loud.

 

[dcg9381]

Can you cut the wires and get a socket on it.

There's a "02" socket with a slit in it for the wires. Sounds like this one grabbing it isn't the issue. I'd soak it a few times a day for about 2 days.

It's usually heat that gets these out.. I've seen a torch used several times, as this one doesn't sound like it a good place for a torch, didn't I see an "inductive" loop heater for just this case where you can't use a torch?

 

[pilotmotor]

Bank 1 is on the firewall side on this engine and bank 2 is on radiator side .
With that being said sensor 2 is always the downstream sensor (after cat) and is never an A/F ratio sensor , always an O2 sensor . So if your code is for :
bank 1 sensor 1 firewall side before cat
bank 1 sensor 2 same side after cat

bank 2 sensor 1 radiator side before cat
bank 2 sensor 2 same side after cat

Bank 1 is always the bank that has #1 cylinder . #1 cylinder is usually the cylinder closest to the harmonic balincer. (the heads are offset roughly by the width of the connecting rod )

 

[pilotmotor]

if its stuck , break / cut it off close to the hex , then use a shallow 1/2 inch drive 6pt socket

 

[Maui]

Bank 1 is on the firewall side on this engine and bank 2 is on radiator side .
With that being said sensor 2 is always the downstream sensor (after cat) and is never an A/F ratio sensor , always an O2 sensor . So if your code is for :
bank 1 sensor 1 firewall side before cat
bank 1 sensor 2 same side after cat

bank 2 sensor 1 radiator side before cat
bank 2 sensor 2 same side after cat

Bank 1 is always the bank that has #1 cylinder . #1 cylinder is usually the cylinder closest to the harmonic balincer. (the heads are offset roughly by the width of the connecting rod )

This car has a 6 cylinder engine, not a 4 cylinder. It has two upstream A/F sensors. One covers 3 of the cylinders, the other covers the other 3 cylinders. Both of these sensors are upstream of the catalytic converter.

 

[Maui]

There's a "02" socket with a slit in it for the wires. Sounds like this one grabbing it isn't the issue. I'd soak it a few times a day for about 2 days.

It's usually heat that gets these out.. I've seen a torch used several times, as this one doesn't sound like it a good place for a torch, didn't I see an "inductive" loop heater for just this case where you can't use a torch?

I've been soaking it on and off for 3 WEEKS with penetrating oil. I didn't drive it for an entire week and just kept soaking it just about every day. No luck

 

[mike93lx]

This car has a 6 cylinder engine, not a 4 cylinder. It has two upstream A/F sensors. One covers 3 of the cylinders, the other covers the other 3 cylinders. Both of these sensors are upstream of the catalytic converter.

A 6 cyl is exactly what that post was addressing

 

[cgrutt]

This car has a 6 cylinder engine, not a 4 cylinder. It has two upstream A/F sensors. One covers 3 of the cylinders, the other covers the other 3 cylinders. Both of these sensors are upstream of the catalytic converter.

Pretty sure you may have transposed some numbers on your initial post and it's causing some confusion. You state Bank 1 Sensors 1 and 2. That would imply upstream and downstream sensors on the same bank. I suspect you meant sensor 1 on banks 1 and 2.

I've been changing sensors lately on my wife's car and have been using an O2 socket as others have mentioned. This will allow you to get a ratchet or breaker bar on it without cutting wires. They're usually available at autoparts stores for under $20.