Crozzer

I’m replacing o2 sensors, which usually calls for dropping the primary cats. As I’m looking at this, it sure seems that the sensors can all be done without dropping the cats..

have you ever tried? Any reason this wouldn’t work, assuming I can reach them to unscrew them?

(the reason I ask is I am convinced I am gong to shear a stud on the turbo, necessitating an engine drop to fix…, and even if I try anyway, those studs seems quite difficult to reach…)



Passenger side looking in from wheel well at upstream sensor. Plenty of room.



Same as above, with light on sensor for clarity.




Passenger side looking at downstream sensor from near the cardan shaft input. Plenty of room! (Also, hey! There is my shiny new vacuum pump!)


^^^ passenger side looks straightforward. Pretty confident I can do the cable routing too. I’m almost decided to try this route. (Which commits me to removing the cat if this fails…)






Driver side downstream, from ATF pan. Tighter but easier than those turbo nuts…

Same as above, without light on sensor, showing the general area better.

Driver side from wheel well. Would need to move those after-run coolant lines temporarily. Maybe need to move the steering wheel shaft?

Same as above, light on sensor.

^^^ driver side a bit more sticky, but still seems easier than removing the cat. Routing the cables seems tougher.


In both cases, it sure seems a torque wrench could get in there, but I don’t have an open ended one, so likely going to just snug em down by hand…

sure could use your thoughts, especially if you have done this before. Thanks!

EricV2003

Not to hard you just need thin arms. I tried but my arms were to thick so my mechanic did it fairly easy.

Crozzer

…then I am hosed ha ha. I am not a small animal. Maybe I can talk my wife into doing it. No.

I finally figured out how to at least get a finger and/or a socket on every bolt, except for 10 o’clock passenger side. It is just totally obstructed from every angle I can figure. Soaking them all in PB Blaster for a spell.

TRINITONY

on driver’s side seems like if u remove hpfp pump and on the passenger side remove vacuum pump, should be pretty easy for downstream.

matthew.a.tanner

This is on my to-do list (primary o2’s)…were you able to get it. Go from top or bottom? I remember a picture of someone with a twisted box wrench to get it. I haven’t even looked…are the secondary o2’s too bad? Happy new year!

Crozzer

I tried an offset claw foot and a ratchet. I think it will work with stubby flared end (which I don’t have). The dealer confirmed they know how to swap the sensors without dropping the cats, and go that route for the more crusty ones b/c they have snapped the turbo studs before. They also confirmed they can drop the turbos and repair the studs w/o dropping the engine, should it be required.

I haven’t given up on pulling the sensors this way, but I may need different tools.

(progress is slow these days, as all the goodwill has been consumed, and the house wants more attention than it has gotten since the pig started hogging all my free time and spare thoughts…)

jeff spahn

I am considering this as well. Will watch this thread

matthew.a.tanner

This is the article that has given me hope.

https://www.renntech.org/topic/46347...cat-o2-sensor/

MM951

It can be done - only one was a bitch and I had a moment of panic when my arm got stuck but with the undercovers and wheel liner off you can get at everything pretty well if you have the tools one should have when owning a porsche.

Matthew Sullivan

Totally doable and not terribly difficult WITH claw sockets, extenders and a swivel socket. Helps to go up through wheel wells - had my neighbor feed from below. 60 minutes tops. (Not a mechanic)

TRINITONY

Was this on a 957TT?

Crozzer

Please pardon me, I’m rather chuffed at the moment.

I did not do it in a single hour, but starting from secondary cats out, and not counting all the time I stared at it doing nothing but hoping not to break it…

I did all four oxygen sensors without removing the main cats in about 2.5 hours. For me the primary motivator for doing it this way was not wanting to break a stud off the blower removing the main cats.

TLDR; done on ramps/jackstsnds with a creeper, an offset O2 sensor tool, a swivel head ratchet, and some extensions to create leverage on that swivel ratchet, oh and for me removing the steering universal joint from the steering gear was key.

Driver side: ironically easier. They are harder to see but easier to work. Remove the single external triple square holding the universal joint to the steering gear box. It helps to line this up before the job. For me, 90 left from center on the steering wheel was just right.

It has to come all the way out b/c even part way in, it holds things together. Take it out, slide the universal joint up the shaft, put the bolt back in so you keep track of it. Spec says to replace this upon reassembly. I plan to, but for now it is torqued to 35 nm, plus a bit, and blue loctited.

This gives you gads of room to work both sensors.



Steering column out of the way? Gads of room. Note the notch that the bolt fits in to keep things put even if it comes loose.

Just slide it up the shaft…

With all that room, unclip the wires from their first clips, so you can slide the slot of the tool over the smallest part of the sensor wire. Hook the sensor with the claw facing straight back - I believe this provides the most leverage. Click on your ratchet and I used a deep socket on straight extensions to make a DIY breaker bar of sorts. You could use a pipe. Both came off super easy with this setup. Take out the sensor. Chase the threads for good measure with the tool that came with the set. Here I added some anti seize while chasing, but probably not necessary. The sensors come with some on the threads too.


Easy peezy

Lemon squeazy


Pay attention to the routing of the cables. Go up top, fish them out. Drop in the new ones. Don’t clip them yet, they need to spin freely while you install the new sensors.



It seems that every automotive connector is an attempt to make it more difficult than the last to disconnect without breaking something. Pay attention here. Look at your new ones.


Yes I broke the plastic “mount” that holds the sensor connectors. Zip tied for now. I’ll try to find the part and replace it later.


Passenger side looks like it will be easier. It is and it is not. The cable routing seems simpler to me. The ratchet extends straight so you don’t need an extension… the rear one is rather easy. The upstream one gave me fits. It is the most visible, and I thought it would be easiest so I saved it for last, but alas it is actually the hardest to reach. For me, a combo of up through the cat hole with my left hand, or turn 90 and up through the wheel well with my left hand, seemed to be the best.



Just pop those clips out of their holes, leaving them attached to the cable. Once you have the cable out, it is easy to swap them to the new one.

Kinda neat to see the thread chaser from the inside.

I got clever here and rigged up a helper to hold the wire so I didn’t have to go up and down to keep it from twisting up. Worked a treat.

Cable helper helps keep things from getting all twisted.


I did not properly torque… I got about 1/2 of a face of a hex socket after hand tight on all of them. It snugs up quick after getting hand tight. I am not a professional, this is a total guess, I’ve never done this before, YMMV. So somewhere between 1/6th and 1/12 of a turn after hand snug.

I also got the secondaries gutted, so they look OEM. Could not deal with it myself so a local shop cut them open, gutted them, and took $2.5 Benjamins. They’ll go back in after this coolant leak is addressed.

Then I did the MAFs. About an hour.

It sounds brutal straight piped and inside for the test fire (secondaries still off for the moment). And I have no way of knowing this objectively, so it is likely a placebo effect… but I’m telling myself it runs much smoother at idle.

Haven’t driven it yet. Oh, and PB blaster smokes a bit after even just a minute or so. Gonna ease into that, as I shot that stuff all over when I thought I was going to pull the cats.

All of this on the advice of a tuner who recommends O2 and MAFs for ladies of a certain age. Even if there are no codes, the variance on these sensors gets rather wide after a decade+ and 80K+.

So yeah, totally doable, not that hard really. Just fidgety, and get that o2 sensor tool.

hatchetf15

^^^^ Well played, sir! [golf clap]

TRINITONY

You get an A!!

Not let's get an A++ . We like pictures, but we LOVE videos . When you have time, post one up on YT, and thanks in advance.

Crozzer

@TRINITONY do I still get an A+ overall even if the video is an F?

this video shows some essential tools and how to reach the sensors without dropping the primary cats for access.

For anyone attempting to replace O2 sensors, I would recommend this over dropping the primary cats. You still have to drop the secondaries, but those are straightforward.

my rationale is less work, and no risk of breaking a stud off the turbos. This is totally doable, about 30 min off, 30-45 min to put on, each side, so roughly 2.5 hours total for me.