What size wrench do i need to take these out?

I had a mechanic replace the before CAT sensor and after CAT sensor on the left side and I went under the car and the AFTER cat sensor looks like an OLD ONE still!!!!

Damn it. I cant really tell but it looks like he replaced the left side before CAT sensor and then the used the other sensor (that was supposed to be used on the LEFT AFTER cat sensor) on the right side instead of replacing it on the LEFT. Damn it...

97 Camaro SS z28 LT1

 

This may be a dumb question, but is there a reason you can not get under the car to find out what size it is?

 

Yea, I'm not sure what size it is, but it was something big like 18mm I think.

 

Yea i really cant because I don't have tools. I wanted to go buy the wrench that I need so i can replace it myself. I'm not going to have to remove anything right? This **** looks hard to get too....I got huge hands.

 

An O2 sensor socket is a good thing to have.

 

buy a cresent wrench. Thats what i always use...

 

7/8"

 

do i got to remove anything down there in order to get to them or do i just need the 7/8 wrench?

 

Heaven help people that work on cars with crescent wrenches.

 

Yupppp.... even en open-end wrench may round off the corners of the hex, leaving you with a major problem. Use the correct tool.... you may be able to borrow an O2 sensor socket. It has a notch to allow it to fit over the wire, and has a 6-point socket, to minimize the chances of damage to the sensor hex. Only problem is they tend to be a bit bulky.

Another thumbs-down on the crescent wrench.....

 

These guys know what they are talking about. Buy the o2 sensor socket you can pick one up at any local auto parts store. It will save you alot of headaches.

 

ive never had to take one off though while it was still on the car so its never been any trouble to me

be careful with it and a cresent wrench wont round off the corners either. It works, btu like you guys said, not the best idea

 

ok picked up a 7/8 from my dad. I was under the car and i am trying to find all the sensors but I only see 3. Isnt there supposed to be 4?


Theres one right under the drivers side before the cat and then theres one on the pipe after the cat. Then on the passenger side theres only one before the cat and then I dont see any other sensor.

I found these 3 like shown in the pic

 

If your car has just one cat, you'll have three o2 sensors. If it has two cats, you'll have 4.

 

My car has 1 cat and 2 o2 sensors.