Replacing O2 sensors

[areznik]

From reading articles about O2 sensors, I followed suggestions of some of you and purchased two O2 sensors for my Q45 1994. I thought it was an easy job to replace them, but it turned out that these sensors sit pretty deep and very hard to reach. If you have any experience replacing those, I would greatly appreciate any feedback. The dealerships wants $103 for replacing both of them and I don't know if its worth for me to pay them this amount.

Thanks.

[DAEDALUS]

It took me about 2 hours of frustration to do them, so it may or may not be worth the cost to you. Get a crow's foot o2 sensor wrench. The deep ones might be too long and hit the engine. I had to go from above for 1 of them, and from the bottom for the other one. The passenger side is harder if I recall. Both take long extensions to reach.

[VA99Q45]

I just replaced my rear 02 sensors yesterday and it took me a couple hours. Without the 02 wrench set, it is impossible to remove the o2 sensor. Luckily, you can go to Autozone and ask to borrow an o2 wrench set. You put down a deposit for $15 and when you return the tool, they refund all your deposit. Pretty cool eh Here is the link to their loan-a-tool program http://www1.autozone.com/servl...l.jspWhen you pick up the o2 wrench set, make sure you get a can of liquid wrench. You need to spray the old o2 sensor with liquid wrench so you can remove them easier.

If I have to do this all over again, I will go to the dealer for this service. If you going to DIY, then be very careful while you under the car.

[Q451990]

Great suggestion on the loaner tools, looks like the crow's foot is included?

I've used the socket style twice with snaking several extensions up between the firewall and back of the engine, but it's a real pain - my neighbor's kids probably learned some new words

Heath

[911/Q45]

I used a 7/8" crowsfoot and the slight extra clearance gave me more flexibility on the angles. The passenger side was easy, the drivers side more challenging. I did them both from the bottom.

[fxjackso]

Definitely from the bottom. In the FSM, there is a picture of the crow's foot wrench in the exhaust chapter, in the special tool page at the begiining of the chapter. This will save you hours.

[elwesso]

I would agree that going from the bottom would be MUCH easier....

When I was doing the plenum and reinstalling the EGR pipe, I kept hitting the o2 sensor with my arm while reaching up to the bolt on the EGR pipe.... Still have scars!!!!

I will remember the thing with the crows foot wrench, im sure that will be much helpful.... Does sears or some other tool place have them where I could add to my repretoire?

[911/Q45]

I got mine at Sears.

[Aus94Q45]

I bought mine at Autozone -- about $8 if I recall correctly. As for the O2's I broke the passenger side from the topside, but removed it from under. On the driver's side, it would seem impossible to get at it from above. I broke that one loose and replaced it from under. As others have reported, mine were not that tight -- it was more a matter of getting the crow's foot on and turning. Small turns both in and out to remove and reseat, due to very limited space. All in all, it required more patience than skill.

[wamQ45]

I got to both of mine from above with a number of woble extensions.

[areznik]

Thanks for your feedbacks. I don't have garage to lift the car substantially to be able to perform any work underneath it, so I paid $100 bucks for the labor. I also did that BG service where they clean the combustion chambers and all the fuel and the air system, at the local nissan dealership. Noticable change is lower rmps on idle and drive. Haven't check the fuel ecnomoy yet. Hope to see improvement from 11mpg that I had before ...

[wamQ45]

I'm getting 17-18mpg with 187K on the clock. How's your car drive? Is it sluggish? Have you gone under the plenum? Knock sensors?

[areznik]

It drives pretty good. I think because I had an injector that was open all the time and oversprayed fuel into cylinder, it may accumulated carbon on one of the O2 sensors. It also burned a bit my cat converter, but it seems that the car drives fine besides ruttling noise from the cat.