My 2001 hyundai elantra periodically will shift hard from second to third gear and then will not shift into overdrive. the check engine light will come on. if i shut off the engine and restart it will shift normally

Sounds like it is stuck in second gear. Overdrive only drops rpm by a couple hundred. In third gears you should still be less than 3,000 rpm.

Second gear is a default gear when the transmission is in limp mode. Is the check engine light on? Does it shift if you manual shift through the gears with the gear selector?

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Check the level in the ******. Make sure that oil is there and topped up if necessary. It should be on the upper marks. Good luck.

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I'm not that user, but go to Autozone and have them scan your computer for the code to your check engine light. It will point you to which sensor to replace, as this is likely your culprit. There are two speed sensors which are critical to transmission shifting on this car. The one I'm familiar with is on the passenger drive axle, but when mine went out (I have a 2001 Elantra as well) I didn't have any of these issues you describe. I don't know where the other sensor is, but that's where I'd suggest starting. Get it fixed quickly though, the web-boards I've read warn that these symptoms can be pretty ******* this little transmission. Good luck!

what can i do to fix the output speed sensor

Did you check the transmission fluid level? If necessary, add fluid. However you probably have a more serious problem. Take the car to a qualified transmission mechanic.

Does the Check Engine light come ON when this happens? Whenever the "Check Engine" light comes on, there is always a DTC (Diagnostic Trouble Code) stored in the ECM (Engine Control Module). You'll need an OBDII (On-Board-Diagnostics) scanner to retrieve any codes recorded/set in ECM. Once you do this and let us know what, if any codes are set, then we can go from there.

You need to access the code and the code should tell you what's wrong.

Go to the dealer and they can do it for you.

hi passing gear is actually your transmision drpping down to second gear.if you hit the gas hard.if you hit the gas lightly it will only drop out of overdrive and go into third and not go into passing gear.

weeeeiiirrdddd. i have a 2001 hyundia elentra gls, and my third cylinder is misfiring as well. my car also revs constantly on idle and in between shifting. it will flutter between 2-3000 or it will just stay at 5000. i replaced my plugs and wires to no fix with my cylinder. autozone also told me that it sounds like my throttle position sensor needs replaced, but every part they try to sell me will not fit and they swear up and down this is the right part...