P1131, the rear O2 sensor, the nightmare!

[FavoriteMystaque]

Also known as HO2S-11 switching (problem) in Ford-speak. I used a Ford Motorcraft DY738 Ford number F5RZ9F472B, perfect fit. Very difficult installation. I followed this procedure http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=v6maint&Number=1023736&Forum=v6maint&Words=replace%20o2&Match=And&Searchpage=0&Limit=2500&Old=allposts&Main=1023736&Search=true#Post1023736 The procedure is correct, except at least on my 1998 Automatic Duratec Mystique, there seems to be even less room back there. My hand could not fit through the tiny spaces. It may be necessary to remove that rear wiring harness, or prybar it. Someone had to jack up the engine in an old post I read. We got it loose with a crow's foot on a long pivoting ratchet and a box wrench for leverage (carefully). Then 1/4 turn at a time, it came out. The sensor wiring actually retightened the sensor when the wrench was lifted, because of the wire twist! It come out, but the new one had to go in with a fuel line hose 5/16 used as a flex shaft with a slot in it to accept the wiring. A "modified" coat hanger was used to support the sensor and guide it into the hole while slowly rotating the hose. It caught and threaded in, and a snugging with the 7/8 box wrench finished it. I really hope the CEL stays off after reset, and the sulphur smell stops!

 

[FavoriteMystaque]

The sensor does seem to have solved the problem I took a look at my sister's 1995 Mystique MTX Duratec, I can reach right in around the back of the engine, without pulling the coil pack off!:shrug: Must be the MTX cars have more room, different engine postioning. I noticed there is additional plumbing on my 1998 for fuel vapor...

 

[waxingmoon]

Yea, I replaced mine on my 98 csvt not too long ago. Earned some busted knuckles and a little experience. Fun stuff. Having an offset O2 socket definately helps.

 

[Pugulis]

I'll have to second that. The offset O2 socket was a great help. I was lucky I got it. When I did mine 2 weeks ago, I went to the store and had a choice between the two different styles and my gut told me to get the offset one. It lets you re-position the socket that extra inch or two that you need to do the job.

 

[2X95SEs]

Is the rear or right roll resistor (engine mount) still in one piece? When it goes, the engine will move towards the firewall and make it hard to put your hand back there.

 

[FavoriteMystaque]

It looked fine, but I might take a closer look. I think the ATX car just has the engine sitting lower and rearward.

 

[2X95SEs]

The tranny mount on ATX cars sags. I had to replace them on both cars. Mine is bad again.