OK, I give, searched and searched but can't find any recommendations.

I need to replace my downstream O2 sensors.

Any ideas on how to get to them without removing the exhaust?

 

Well with extensions I got my O2 socket on the sensor but it justs wants to round off the sensor, put oil on it last night and again this morning.

Please tell me I don't have to remove the CATS to get this replaced....

 

Access to the lower sensor from below is very restricted, the gap between the transmission and exhaust is only about an inch and a half.


This picture gives the wrong impression of how bad the access is.





Access was done this way with a wobble on the O2 socket and a couple of extensions.





I first tried it with a 3/8th set up which ended in failure.





So I moved on to 1/2 inch which was able to break it free.





I was able to reach down from the top with my skinny arms to screw the new one back in then tighten from below.

 

I give, I don't admit to defeat often but I can't get the O2 sensor off. I've soaked it in penetrating oil and can get my O2 socket on it firmly but the socket keeps slipping and is rounding off the sensor hex. I afraid if I work it any more no one will be able to get them out.

My O2 socket looks just like the one above in RD's photo's. With extensions I am able to get my 1/2" drive squarely on the sensor by extending back behind the trans. Can get my socket wrench on it with a cheater bar and have enough room to get about two to three clicks on the ratchet.

Could they have made the connectors any harder to get to behind the throttle body. Mine is the left side downstream sensor and the wire is so short after getting the plug off the holder it's dang near impossible to get both hands on the plug to undo it. Then getting a VOM on the pins to confirm the heater circuit on the sensor is shorted was another story.

This one kicked my a@@s....

So, I'm taking it to an Indy to see what they can do..this really pisses me off.

 

Try this first, cut off the wires and use a 6 point deep socket, that way it may not slip.

 

I have used 3 different O2 sensor tools and none of them would budge the sensor the would spring open and slip so I ended up getting an 4 point open end wrench and used an air hammer on the wrench to get it loose. A bit unorthodox but it worked. I was told an 8 point box end would do it but was not sure the plug would go through the wrench. If you get one be sure it is a quality wrench or you will have the same problem. Also SnapOn has a reinforced socket that works with an air hammer.

Another option is to spray the O2 with PB Blaster then run the car for about 10 to 15 min and try it with what you have and if that does not work cut the lead and use a regular socket. If that does not work pull the cat.

 

Thanks RD and Gus, went out looking for a better O2 socket and there are none to be found on Maui. I did see one in the NAPA catalog that had a narrower cutout so there was more wrench surface.

What would happen if I cut the leads and still could not get it off? Would the car be drivable for say 20 miles to get it to a shop?

How about if I cut the leads and put my deep impact socket on it and use my impact driver?

I also saw the TSB on Gus's site warning not to exceed 52 ft lbs when removing to prevent thread damage, should this be an issue?

I did soak it in PB Blaster yesterday and again this morning about 1 hour before I tried to remove it. Did not try the heat cycle, if I have a go at it again I'll soak it the night before and again the next morning and heat cycle it just before I try to get it off.

I really, really don't want to take this issue to a shop so will have another go at it next weekend.

Just to be sure, this is a left hand thread, correct?

 

Any shop would be happy to remove it for you. You do not need to take it to Jaguar.

Gus
www.jagrepair.com

 

Yelp I'm sure, seeing as there is not a Jag dealer on Maui that's a good thing. Not that I would go there if there was one.

Have all ways done my own work, that's what is pissing me off about this O2 sensor. Guess I'll let it sit till I get time to attack it again.

 

What would happen if I cut the leads and still could not get it off? Would the car be drivable for say 20 miles to get it to a shop?

No Problem with that. You can give it a try by disconnecting it now.



How about if I cut the leads and put my deep impact socket on it and use my impact driver?

Yes, try it, and also try a breaker bar, I needed to use my big one to break it free.


I also saw the TSB on Gus's site warning not to exceed 52 ft lbs when removing to prevent thread damage, should this be an issue?

I estimate that I needed at least 80ft 1b to break mine free and the thread was fine.


I did soak it in PB Blaster yesterday and again this morning about 1 hour before I tried to remove it. Did not try the heat cycle, if I have a go at it again I'll soak it the night before and again the next morning and heat cycle it just before I try to get it off.

I have never found any penetrating fluid to make really tricky nuts/bolts come off easily.


Just to be sure, this is a left hand thread, correct?

It is a normal thread. Do you have a replacement ready?

 

Thanks RD

Yes I have replacement O2 sensors on hand, have verified all wiring and correct parts.

As stated the O2 socket just slips rounding off the sensor hex, I had my long breaker bar on it.

Will have another go at it next weekend and will report back, this time will try as follows:
Heat cycle the sensor by running the car for a few minutes, try O2 socket with breaker bar. If that does not work will try O2 socket with impact driver.
If that does not work will cut wire and try a deep impact socket with Breaker bar or impact driver as needed.
If none of this works I guess it's time to look at removing the cat.

Wish me luck!

 

Well after all that fussing, cussing and crying like a little girl I'm happy to report my manhood has been restored and the O2 sensor demon has been conquered.

I took pic's will do a quick write up in a day or so but basically I cut the wires and used a 22mm deep socket, came off like butter. Worked so well I did the other side in less than 30 minutes.

All codes cleared and all is good with the Jag again!

 

it's rarely the sensor but the socket, the o2 sockets are great for installing only.
The new one did have anti seize on it for next time correct ;-)

 

OK, to remove the lower O2 sensor from either side...

1 - remove the Throttle Body air intake Housing
2 - locate the 4 O2 Sensor plugs behind the Throttle Body, 2 grey and 2 black. The black ones go to the lower O2 sensors. Pull straight up on the plug assembly and it will come off the mounting stud.
3 - I tied a length of yellow masons string on each end of the plug for two reasons, 1 - so I would not loose them in the tangle of wiring and 2 - so I could use the string to pull the new plug up from the bottom.
4 - disconnect the plug assembly, get under the car and pull the O2 wire down.
5 - Cut the wire at the O2 Sensor. I used a long serrated knife as there was no room to get a pair of wire cutters to the sensor.
6 - I used 1/2" drive tools, using a 22MM or 7/8 deep socket with 1 ten inch and 2 six inch extensions, total extension length 22 inches, you can get a ratchet, I used my Torque wrench, onto the extensions rear of the transmission where the drive shaft attaches.
7- remove the sensor.
8 - Using the same extensions but with an O2 socket I taped the O2 sensor and the wire along the extension using household Scotch tape. This makes it easier to re-attach the sensor and the tape breaks off easily when finished. The torgue for the O2 sensor is 32 ft. lbs.
9 - using the yellow string pull the plug back up, this is a little fiddly
10- Connect the plugs and re-attach to the holder

Your done!

 

I ended up removing the cat off the exhaust manifold so I could use a full box end wrench. This lower sensor was pretty stuck, and I figured rounding it off would make it much worse.

Part: DENSO 234-4798 Lower Oxygen Sensor
Code: P0037

Another thread here: p0037-new-engine-light-110767/

Thanks for sharing.