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2001 Kia Optima SE, 2.5 V6
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Discussion Starter #1
:lol: Both the input speed sensor and the output speed sensor are located below the air box (Air cleaner) on the top of the transmission. They are very easy to replace. If your ECM reports a P0715 code its likely the input speed sensor if it reports a P0720 its likely the output speed sensor. Although they could each trigger the opposing codes. Its best to test the sensor using the processed outlined at Kiatechinfo Sign up for a free account and look under DTC (Default Trouble Codes) You will also want to check the connectors for broken or deteriorated wiring and test the connectors as outlined in the same section. After Replacing the Sensors You MUST Reset and reprogram the base line for the TCU (Transmission Controll Unit) To do this disconnect the negative battery cable for 10 or more seconds, then reconnect the cable and secure it. Get in and start the vehicle and drive it at a slow speed allowing it to shift into all 4 gears, slow the vehicle to a stop and accelerate at moderate speed allowing it to shift into all 4 gears, slow the vehicle to a stop, accelerate at a high rate of speed (FLOOR IT) allowing it to shift into all 4 gears. Enjoy your newly repaired transmission. As a side note in my experience if the TCU is not reset the transmission will exhibit the same symptoms as before but will not set a trouble code.
 

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2001 Kia Optima SE, 2.5 V6
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66 Posts
Discussion Starter #2
I have run into another symptom the transmission locks into fail safe mode and doesn't set a trouble code. After testing both sensors with the car moving. ( I ran a wire from the sensors into the car, connected each one to a DMM set to 20VDC they should test around 2.6 VDC -- 5 VDC and variable depending on speed when the car is in gear and moving the voltage should MATCH each other if the sensors are reading properly). I discovered when they transmission goes into fail safe my output speed sensor shorts and locks at 5.0 VDC which is the reference voltage the sensor is bad.
 

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2002 Kia Optima SE6
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1 Posts
My 2002 KIA Optima shifts fine when engine is cold. When it reaches normal operating temp it will not go into 3rd or fourth gear and a couple of times when I slowed down it BANGED into 1st. After reading your post I'm guessing it is either the output or input sensor or both. Can I change one at a time (financial constraints) and if so which one is more likely to be faulty?

Very appreciative of your help Thnx....
 

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2001 Kia Optima SE, 2.5 V6
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66 Posts
Discussion Starter #4
Sorry for the very late reply I haven't been on the forums since I started school. Yes you can replace the sensors at different times. Be sure to reprogram the shift points by disconnecting the battery (it should be anyways if your working on the car) and leave it disconnected for one minute.
Drive vehicle from stop, allowing transmission to shift through all gears at light throttle. Repeat procedure ten times (cycles).
Repeat step 2 at mid-throttle opening.
Repeat step 2 at high-throttle opening.
If this does not fix the problem replace the other sensor and do the TCM relearn again. If the transmission still does not shift properly replace the TCM. The TCM is located behind the center console on the floor and on top of the ECM.
 

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2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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47 Posts
I don’t know about the others but this information will come in handy when I replace mine in July, I'm dealing with the dropping to third gear for now. Lack of money right now. These sensors are 140 bucks each from the dealer.

After it drops to third gear and if I drive it for 30 minuets I can stop the car turn it off take the key out and then I have to wait just a min or 2 then restart the car and it will shift right but the check engine light stays on until I let the car rest for 3 hours.
 

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2001 Kia Optima SE, 2.5 V6
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66 Posts
Discussion Starter #6
Those are the exact symptoms I had. Mine only got worse and worse until I finally replaced the input speed sensor, then swapped out the TCU, and lastly replaced the output speed sensor. I had the added problem of not getting a check engine light after replacing the first sensor. The transmission would go into fail safe and I would not get a light that is why I replaced the TCU however it was the output speed sensor that was causing the issue.
 

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2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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47 Posts
Well I hope it holds out. I have to take my family to Orlando in the latter part of June. When we get back I will change the Sensors out. I took the car to my local Advance Auto Parts store and they hooked the reader to it and showed me that Both Sensors need to be replaced. But like I said I hope it will go the way it is until we get back.
 

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2001 Kia Optima SE, 2.5 V6
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66 Posts
Discussion Starter #8
Your gas millage will suck and keep it under 60. Change your Timing belt yet?
 

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2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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yeah changed that at 97,000 miles lol cost $3000.00 Top half of engine had to be replaced because the timing belt came off and jacked the engine all up.

The Dealer tryed to hit me up for $500.00 more for spark plugs, wires and ignition coils lol that they didn't replace. they got cought trying to take my money. You have to watch the Dealer they will rip you off in a heart beat.
 

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2001 Kia Optima SE, 2.5 V6
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66 Posts
Discussion Starter #10
I replaced mine my self and got the belt one tooth off. I rebuilt the top half of the engine last summer. I have a thread here about it. Oops!
 

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2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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I don’t have the room to do all my repairs or builds myself. something that big, I will just have to shell out the cash to get it done correctly.
 

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2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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How long will it take to replace the Sensors? 1 hour or 2???
 

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2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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I asked a dumb question lol. After I posted this the input and output sensors came in and I just went a head and did it lol. It took me 30 mins but the air intake hoes tore. I had to try and give it a quick fix for now. I did it driving test, Slow through the gears then moderate then hammer down. During the slow and moderate speeds it shudders while going in 3rd but if I hammer down it slides right through. Possible due to the tear in the intake hose???
 

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2001 Kia Optima SE, 2.5 V6
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66 Posts
Discussion Starter #15
I can't see a torn air hose causing a shift flair. Did you disconnect the battery as per the instructions? I would try the re-learn procedure again and see if the problem persists. If it still flairs a little bit, drive it for a week and see if it gets worse. When the sensors were damaged and the transmission was not shifting properly there is a chance that one or more of the clutches or synchronizer's were damaged. If that's the case live with the shift flair and get used to having overdrive again.
 

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2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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47 Posts
I just drove it to get some ice from around the corner and it shifts proper now. I glued the intake hose with gorilla glue and now I feel like I have a new car again except for the AC not working lol (Just that Fan Switch and grounding issue) but I have fixed the Passenger window so it will go up and down now. But the car Drives great thanks for all the help.
 

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Recently, I fixed my 2001, Magentis 2.4l, Auto transmission for code P0720 - output speed sensor circuit, which was throwing check light ON and sluggish gear transitions. The sensor was malfunctioning for a long time since I was feeling gear transition hesitation for a long period (almost for 2 years). Only few weeks back, I got check light ON and P0720. This may be because of poor diagnostic algorithm for this sensor.
If you could see the photographs attached, you will find that it is very easy to fix it. Basically, I needed to remove battery, air filter assembly as shown in the photograph. The two sensors are located on the top of the gear box housing.
Luckily, I found the parts on ebay(foregreen) (both input and output speed sensors) at very cheap price ($86) including shipping) compare to dealer price of ($225) only for output sensor. I changed both of them. Since, I changed them, my car runs smooth and there is no hesitation in shifting gear.


hopefully, this will help someone who is trying to fix the issue by himself.

Photgraphs attached.
1. OutputSpeedSensorCloseup.jpg
2. OutputSpeedSensorLocation.jpg
3. OutputSpeedSensor_P720.jpg
4. P720_Input_Output_SpeedSensor_Location.
 

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Registered
2001 Optima SE 2.5 V6 w/248,000+ miles, Harley Davidson Sportster XL1200C
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47 Posts
input and output sensors link to Rock Auto >>>>>>> Link
Well if the link doesnt work properly just click KIA then your year then Optima then v6 then search for speed sensor I bought the Auto 7 parts 38.79 for the input and 46.79 for the output sensor. got them in 3 days.
 
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