I pulled the output shaft speed sensor to add a quart of transmission fluid. Now my tl is shifting funny and actually made the check engine light come on. Any ideas?

 

A few questions come to mind.

why was the fluid low?
why not use the fill hole?
what kind of fluid did you use?
What codes are setting off the CEL?
How many miles on the transmission?

 

I had to change out one of the axle shafts. I don't have a fill hole on my transmission. I used Honda fluid. It's showing P0720 output shaft sensor. The transmission has 70000 miles on it. Was driving fine for the past week until I pulled that sensor and put fluid in it.

 

What do you mean no fill hole... its right up top near closer to the firewall with the word "FILL" on it

 

There is not one on this transmission. It is one from Japan if that matters.

 

This is the speed sensor. How could this happen?

 

I gotcha. Oil jet kit covering fill hole.

Considering the code points to exactly what you had removed there must be something amiss with how you reinstalled it or it just coincidentally crapped out. You sure it's seated properly. Double check wire connectors(possibly bent pin).
Dunno if there's a way to bench test the sensor itself.

 

Yeah it's the oil jet kit.

 

Ahh...

Then you can also pour in via the dipstick. Overfilling sometimes causes bad shifts as well

 

that picture is too blurry to see anything. Is it broken?

 

It has been worn down to the inside of the unit. It has no plastic on the end.

 

uh oh! So all the plastic and metal in that sensor are ground up inside the transmission?

I would venture a guess you now have 260LB paper weight bolted to your engine. Who knows, you might be able to drain and fill
a few times, pull and clean all solenoids, change filter and pray but..............

 

Aside from the above have you actually checked that you have the correct level of fluid in the tranny? You have to check with the car warmed up, right after driving it at speed, with the engine off. Cold readings are not correct.

 

I have checked the fluid level per the way you stated above. The level is now correct.

 

Is that sensor all ground up inside your transmission?

 

No it's not. I drained it and didn't find any pieces. I'm not sure what happened to it.

 

Was the sensor in that broken condition when you put it in the transmission after putting a quart of fluid in? If the sensor was fine when you put it in, then the only place those parts could be are.........
wait for it.........in the transmission.

Do you see what I'm getting at? Foreign junk floating around inside a transmission is not good.