Another approach:

There is a way to do this from inside the engine compartment on 1999+ 3.8l Windstars. Tedious & possibly gonna scratch your arm up, but easier than pulling motor mounts and exhaust pipes.

Location: Directly underneath the middle spark plug on the back of the engine - about 3" down, and inserted into the top of the transmission. There is a metal shield that is held in place with the same hold-down bolt that secures the sensor.

Access:

• Clear the right side of the engine compartment - the rubber piece & left side of the air cleaner housing. Couple of 5/16 hose clamps, couple of sensor plugs & 1 vacuum line to the back of the rubber connector.
• Throttle cables & mount - release the 2 cables & 2 10mm bolts for the mount.
• I would strongly suggest pulling the cowling! As every Windstar owner knows, this cowling is the biggest impediment to getting access to almost everything at the backside of the engine. Removing it isn't a big deal (especially after you've done a few times ;)), and is detailed in various postings here on Answers.com
• Optional: release the coilpack from its 3 mounting bolts (weird size, something like 7mm)

  NOTE: don't rush and forget to secure the radio noise capacitor thingy under the leftside hold down bolt.

Getting at the bolt:

• Socket extension combination to clear the angles - 8mm socket + universal + 6-8" extension + 8-10" WOBBLE extension.

  TIP: tape the joints together so your extension assembly doesn't come apart as you're pushing & pulling it up and down

• The opening you're aiming for is to go down alongside the middle sparkplug. There's plenty of interference what with wires & exhaust manifolds, but this is the opening that aligns with the top of the bolt.
• Your arm, if it's long enough (thank goodness I have monkey-arms!), can go down to the right of the braided covered heater hose and turn left to the backside of the engine.

  Once your hand is down there and has figured out where things are, you're ready to use it to guide the socket into place & onto the bolt

• Use your left hand to find the correct opening and lower the extension assembly.

  This is a totally blind operation! You will never see the pieces you're working with.

• Have a 2nd pair of hands to help! They come in really handy when it comes time to operate the wrench.
• NOTE: because of the angles, the top of the socket extension assembly is going to end up real close to the firewall - thus the universal + the wobble to accommodate the angles from above.

Assuming you don't dislocate your shoulder or bleed-out from scratching your arm to shreds, you should be able to get the 25mm long bolt out!

Lift and remove the cover, and the sensor should rotate in the open pretty easily.

Removing the sensor: This is the hard part because you can't easily get upward pull as you twist the sensor in its opening! Just keep twisting and lifting - it'll come out... eventually!

This is one of the most painful, awkward & frustrating things I have done on a vehicle!

But in my circumstance, well worth the effort.

Btw, don't do this unless you know for 100% sure your sensor has failed - you're not going to enjoy the experience.

Best of luck! :)

Answer:

Forget what the manual says! It will have you remove the exhaust pipe which is hell if its old and rust; and after that you will have to feel your way around the sensor as the angle is bad. Also, it puts you hand in a cramped position to try and ratchet the mounting bolt on the sensor which is on top and away from you.

I had to change mine and this most direct approach that is least problematic. The sensor is located on top of the transmission right behind the passenger side rear engine mount. Jack up the car and support it safely on a jack stand. Then remove the passenger side front wheel and fender guard to get access to the engine and mount. You got to remove the mount and mount supporting bracket on the engine to get enough clearance to the sensor (which requires lifting the engine some. Last resort you can use your floor jack and a block of 2x4 wood to do it only don't lift on the oil pan or crank shaft pulley. I tend to use the area where the oil pan bolts to the block. Make sure to unbolt the bottom of both the front and rear engine mount first and then lift slowly and carefully so not to cause damage anywhere). As soon as I remove the mount, I usually lower the engine back down to be safe as floor jacks can be unstable.

This part is difficult to describe as I can't accurately remember, but, the transmission has a hump or cap on top of it. You'll see the sensor plugged into it from the opposite side that faces away from you. You'll spot the sensor after removing the mount and you'll see what I am trying to describe. Its common sense. There is only one bolt and you have to feel around the sensor for it where it plugs into the hump/cap. I don't remember the size of the socket but you can research that. Because of the confine space, use a small socket wrench.

Make sure you clean and wipe the area before removing the sensor. Otherwise, debris can fall inside the hole where the sensor goes and re-installing the sensor can be sticky. So a mild lube on the sensor housing (not the gear!) helps to slide it into the hump.

If your car is really old, it might be wise to purchase an extra pigtail connector that plugs the car computer into the sensor. Because the sensor is so close to bank 1 of the engine, the heat and weather overtime can make the pigtail brittle and it can break during unhooking. That happened to me.

I agree with the below statement, its a zippy little car, and you can do so much bolt on stuff yourself at your house if your into working on it and you just watched the fast and the furious :P ha but stock the car has 130hp at 53,000rpms which is decent for an American tuner. mine right now has a turbo kit from focussport, and after the dyno tune i have 235hp to the wheels, she runs in the 14s at the track, it is of course recommended to have it professionally installed but it took me 3 days at about 3hours a day and i hooked it up, that's probably the best part about this car is that its so easy to fix up the engine is so small and simple to work with i also drive a 99 mustang gt and that i do take to the shop but get a focus they're very nice

The seat belts ratchet and keep getting tighter even when replaced by Ford. It constantly goes through emission sensors and gives erroneous engine light errors. Not to mention the recalls, many recalls. You have to be a contortionist to put on your seat belt or to change the oil filter. Many unexplained rattles while moving. Extreme static discharge from the upholstery, don't believe me? search the web it's true.

The cheap brake pads that Ford put on this car expell a masive amount of black brake dust that is ruining my aluminum wheels and are very noisy and groan loudly when it is wet or dry, this generates many strange looks from people on the road and makes you ashamed that you are driving a Ford.

I would not recommend buying any focus, as a matter of fact I would not recommend buying any Ford product because of all the problems myself and my family have had with the Taurus-Windstar-Focus, we have had many fords over the period of 5 decades and can't rely on Ford since the early 1990's.

Thank You Ford motor company for directing me to purchase a Japanese car in the future. I am looking forward to owning my first Camry soon.

Answer

Well i like my 2000 zx3 But stock, it doesn't like hills. I have to climb them at 4500 rpm haha. Plus I've had quite a few problems with it. Both that are my fault and factory defects. The e-brake cable broke on me but i saw that coming when i bought it. The line was just old and rusty. Now it only locks up one back tire but that's all your really need. :D Plus the front stabilizer bar went bad, but that was from me pretending i was in the WRC and jumping it. A new one cost me like $125. I don't jump it anymore. haha. But it has this defect going... At random times, when i hit the gas, the rpms will drop. But if i let off in time, it cuts back to idle. when this happens, (always when I'm driving down the road) I eather press the clutch in and play with the throttle, or i shut the car off and start it back up. They both usually work but the problem keeps showing up. I figured it was a bad fuel filter so i changed that. (by the way, changing the fuel filter in a 2000 focus zetec was the easiest thing i ever did.) the problem went away for a while, but come inspection time, I had to get a new flex pipe to pass immitions because my old one was shot. haha Right after i got that done, it started the problem again right away. So i figured the computer wasn't use to the new backpressure. So i unplugged the battery for an hour to reset the computer but it STILL dose it! I'm gonna take it to a dealership and get the computer checked to pin point the problem. and while I'm there, I wanna see if they can program the speed Governor and the rev limiter out of it. And program the fan to kick on earlier so the engine will run cooler. (cooler engine = more acceleration and better gas mileage :D). Not to mention the latch for the hatch froze up and it's stuck shut. I tore it apart to try to hit it with pb blaster only to find that the latch and the electric motor is sealed in a black box that you can only remove when the hatch its open. Once i can get this all fixed up, i do look forward to building it up. I wanna get a k&n intake (turbo's coming later), Racing plugs and wires, stronger cylinders, high compretion pistons, aftermarket exhaust and a racing clutch kit. But first things first. haha

Answer

I think you get what you pay for. It entered the market as a just over $12,000 (CDN) with a peppy little 16 valve engine. I bought my '01 ZX3 about 4 months ago just to drive back and forth to work. This little puppy is going on 9 years old and is sitting at around 120,000 kms - and other than a dash light, oil change and a couple smaller items (wipers, floormats) it's worth the little money I paid! Every single manufacturer has its flaws (yes even the beloved Japanese ones) so if you got stuck with a lemon I can totally sympathize with that (it's happened to me!). I think for the money it's a great little car to bomb around in and race back and forth to work. Hey even my 15 year old son is itching to start driving it next spring! If you ask if I would recommend it - then yes I would - but only as a second vehicle for your wife or kids....