Replacing O2 sensor

[ModCougar]

I have been getting the code P0161 [O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)] for quite a while now and the CEL is really starting to annoy me. I can clear the code but it comes back on after a day. So I guess I need to replace the O2 sensor. I think Andy [BENNET] said that it is the front lower O2 sensor. That is the one in the exhaust manifold in the front of the car, correct? Right up there by the cooling fan? I need a how-to on replacing that sucker. Is it possible to do without taking a bunch of crap off or pulling the engine? It looks like both of the O2 sensors in the headers would be difficult to replace with as little clearance as there is to them. Anyways, somebody please help if you have had experience with changing this O2 sensor.

Oh, and is there a good place to get these A/F O2 sensors? I can't really find them cheaper than $50-60 anywhere. Dang...

1999 Mercury Cougar V6 MTX

[wadespencer99]

Yes, that is the lower front sensor, and is cake to replace. Unplug the harness, and unscrew it from the manifold...it doesn't get much simpler than that.

[ModCougar]

Well...I guess I knew how to do it if there is enough clearance. I suppose that is really what I needed to know. Anyone happen to know what size it is. Should I just spray it down good with some penetrant first and use a wrench? Because I don't feel like going and getting the O2 socket. Well, I guess I will just try to get a wrench on it then. Now I need to buy an O2 sensor somewhere. Any recommendations?

[B3NN3TT]

A nice big crescent wrench will do fine.

[wadespencer99]

B3NN3TT is right, but I believe it's a 22 or 23mm. This really isn't that hard...just crawl under there and do it.

[ModCougar]

I realize that it isn't that hard. I was now asking if there are any recommendations as to where to buy the correct O2 sensor or any recommendations on brand. It looks to me that $45-$65 is the general range for the prices on them after checking teamfordparts, autozone, and car-stuff.com. I found one by Denso for $45. I found a bunch of Bosch, and some other brands (motorcraft, delphi, SNG) for between $50-65. Anybody know of a better price or place to get one? I'm sure it doesn't matter much, but I won't be getting to this for a couple more weeks so that's why I might as well ask.

BTW Wade, I absolutely love your '02 F150 Flareside Supercab FX4 truck. I've been looking for a nice truck and that would be sweet to have. Looks like you did a nice job on the rebuilding of it. I was seriously considering working something out with you to buy it but then a good deal fell in my lap for a 1993 Dodge Stealth R/T Twin Turbo. Not exactly what I was initially looking for but it's going to keep me from buying a truck for a while. But I wish you good luck with the sale! It sure is a nice truck.