Flashing O/D and P0720 Code

My '97 Ford Explorer may need a tranny...but I am trying to avoid that (something about the high cost).

Details: Driving down the road, minding my own business, and wham...the O/D light starts to flash. After a restart or two, it stopped. Ok, minor hiccup, no problem. Wrongo. Check Engine Light came on. Now, i don't know the exact code, as the AutoZone dude just said I needed to replace my speed sensor switch. $15 got me a new one, and I was on my way.

Two days later, O/D flashes briefly, then stops, and Check Engine Light is back on. This time I get to see the exact code P0720 Output Speed Sensor Circuit (probably the same as the first time).

I don't have a heavy foot, but as I drive, the RPMs will occasionally jump as the tranny shifts. It is very momentarily, and other than this (and a noticeable decrease in gas mileage), all seems well.

I've read as much as i could find on P0720, some suggest replacing the solenoid.

Forgot the miles: 137K and going strong!

Make sure that you are replacing the correct switch - the OSS (output shaft speed ) sensor is different than the VSS (vehicle speed sensor) that sends a signal to your speedo. Also, check the wiring carefully because it could be a wiring problem.

In the picture, #15 is the OSS, #14 is the VSS (the VSS is on the transfer case if you have 4wd)

my 2000 explorer sport started doing that at about 90,000. it wouls kinds hang up in the low gear between 35-40. i put a bottle of lucas trans slip in it and it fixed it good. then after a month or 2 it started doing it again but between 20-25. so i took it in to a local trans place and they put it on the rack and plugged the diagnostic in and said several things neede replaced. i went ahead and had a re-build done.after $1500.00 its like new! but my o/d light would flash like that.

Thanks to both of you...6 auto parts stores and 2 Ford dealerships later, no one has this part. They can order it, but it won't be fixed today
I'll keep you posted.

that sucks huh? well keep your head up! you will get it.good luck to you man. yea keep us posted.

fuzzie said:

Thanks to both of you...6 auto parts stores and 2 Ford dealerships later, no one has this part. They can order it, but it won't be fixed today
I'll keep you posted.

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You may want to remove it and see if there is metal debris sticking to the magnet and also check it for any damage before buying the new one.

Well my mechanic couldn't get it out...torx head and I think he *****ed it up. Went to tranny shop (should have started there), and they claimed the sensor isn't bad. Good news, right? Except my mileage is still in the can, 11 mpg compared to 19-20.
Yikes!