Mazda 6 Forums banner

P0715 Issues

10761 Views 6 Replies 4 Participants Last post by  superj
A couple of months ago, the car dropped into thrid, AT light and CEL came on. I stopped the car turned it off, checked and reset the codes (I keep a bluetooth ecm reader in the car and have the Torque Pro app on my phone). I had a code P0715. It was fine for a while, then it happened again. I replaced the Input Speed Sensor with Dorman Part #917-649 .

It was fine for a few weeks and I thought it was solved, but last night it dropped into third again and the light came on. I pulled over, turned off the car, restarted it and it was fine for a few minutes and did it again. I did the same and cleared the code and it was fine for the rest of the night.

Any suggestions?
1 - 7 of 7 Posts
You need to have the transmission codes scanned with a dealer level scanner, the generic P0715 code may not be what you think it is. Mazda very likely has their own definition for P0715 and there could be other codes in the transmission computer that you cannot read with a generic scan tool.

Also, P07xxx codes are almost always indicators of internal issues with the transmission. Very often it is one of the solenoids in the valve body, but never guess. Get is looked at as soon as possible, you are risking a bigger problem by not finding the real cause of codes.

Also, check the wiring to the speed sensor.
Through further looking around, I see that I may have replaced the wrong sensor. There are three sensors on the top of the trans, which is it that normally sets the P0715 code?
The one I replaced is the one that RockAuto listed as the input speed sensor. It is the first picture below.
Now that I look at the manufacturers description, it looks like it's the sensor for the speedometer.
It appears that others have been replacing the sensor in the second picture. Should I be replacing the one in the first picture or the second?
There looks like there are two of the second sensors on the top of the tranny. Which is the one to replace? The front or the rearmost; or looking from the left is it the left or right.


See less See more
I went to the dealer.
It turned out that I had purchased and replaced the wrong sensor. It is the sensor in the second picture that I should have replaced.
I bought the new one at the dealer. It was $132 for Part Number FN01-21-550. I realize that I could have gotten it ~$100 cheaper online. Sometimes it pays to have the expertise of the dealer and know that I am getting the right part.
I looked at the transmission again and there is only one of that style sensor. It is on the front half of the top of the transmission. You can change it without removing anything. It is much easier with the airbox out of the way. I vacuumed the area real good before removing the sensor to get all of the sand and other dirt out of the way and keep it from falling into the transmission.
And did this solve the problem? I'm having the same issue...
I ordered that pn FN01-21-550 to replace my sensor for that p0715 input turbine speed sensor code on my 2005 m6i (i is the 4 cylinder, right?).

It says it should be here wednesday. Until than i am using forscan with my bluetooth obd dongle to flip the light off. It comes on every other day, or so. When its on, the check light pops on the gage cluster and the car won't shift up to fourth, as well as shifts very oddly for the other gears. I think it shifts ok in manual mode but i will have to try it again if it pops before the part gets gere to be sure.

Hopefully it gets here on time. I am driving to fort lee virginia on friday so i will be gone for about 9 or 10 days and wont be able to work on it.
update for future readers:

the pn fn01-21-550 fixed my issue. so if you get a check light and the car shifts weird and won't go to top gear, this a cheap easy part to swap that you can get on amazon. my car is old enough (05 model) that i buy generic name brand parts for it, as i have for all my older vehicles, and expect no troubles, like the previous parts have been trouble free.

i use a bluetooth dongle obd2 adapter and the forscan app to check everything. if you just happen to have the adapter in car and app on your phone when the check light pops on, you can log in to the app and reset the light and the car will go back to shifting normally for another day or two while you wait for the part to be delivered.

i use an elm327 bluetooth adapter that plugs into the obd port on the cars. its a clear blue generic one from ebay or amazon but has worked on every car or truck i have tried it on with the torque light app, or the forscan app. it worked on mini coopers, nissan trucks, ford escapes, geo metros, mazda vehicles, ford vehicles, and probably many others i am forgetting. i have actually bought two of those adapters because i accidentally left one plugged into my 01 nissan frontier when i sold it. this particular obd adapter generally sells for about 15 bucks on ebay and amazon so if you need an inexpensive one for your car, look into that. and use the forscan app on the first gen mazda6 as it works a lot better than the torque light app does.
See less See more
1 - 7 of 7 Posts