2004 Mazda 6 Transmission issue

Recently, the transmission on my 91 Pontiac went out, and since it would cost more than the car was worth to fix, my wife and I decided to get a new (to us) car. After quite a bit of hunting, we found an '04 Mazda 6 with 94,000 miles, and we both really love it…

Except for one thing.

We’ve had it two weeks, and the engine light will randomly come on. Sometimes, while this is on, the Automatic Transaxle light comes on, and the car locks in 3rd gear, until the car comes to a complete stop, where it jumps directly to 1st. Sometimes the AT light will turn off at this point, while others it will stay on, and as soon as you reach third gear, it won’t come out. Manual is completely disabled, at this point. The only way to definitely stop it, is to turn the engine off, wait a few seconds, and start the car again. However, the AT light will sometimes come back on as soon as you reach 40 miles an hour, kick the car into third and lock it there.

Did we get a lemon? Do I have to pay for an entire new transmission? Was I complete dolt for passing up the after market insurance?

First, check the transmission fluid level. Then have the computer scanned for trouble codes. Until you know what’s wrong you won’t know how to fix it.

Did this used vehicle come with any sort of warranty? If so, now’s the time to use it.

A lemon means an unfixable car, so not a lemon.

You likely found the reason this car was sold off by another owner or dealer unfortunately.

My daughter bought a 2005 Mazda 6. At about 15,000 miles her car had a shift problem. I don’t know if she had all the same symptoms as you. When she called the dealer they told her to bring it in they knew what was wrong. Apparently there was a computer issue that Mazda already knew about. The issue wasn’t mechanical but computer related. The car’s been fine since (about 70,000 miles). This is worth a call to the dealer and maybe your fix will cost a few bucks but not near the price of “an entire new transmission”.

I’ll try it. Checked the fluid, and everything was fine. Was thinking about taking it to Autozone which is advertising pulling codes for free, but I’ll contact Mazda to see if they know what it is.


I was mistaken, my daughter’s car is a 2004. She bought it new about the time the 2005 models came out. So the cars are the same model year. Good luck!

I was able to take it to Autozone, and they did indeed scan for free. Apparently, I have a “Input turbine speed sensor malfunction.”

Probable causes (according to them)

  1. Open or short circuit condition
  2. Poor Electrical Connection
  3. Failed Input Turbine Speed Sensor

How easy a fix is this?

Its not hard at all, the TSS or Turbine Speed Sensor is located near the bellhousing on the transmission case. You will see the wiring connector going to it and a bolt which holds it into the transmission case. You can probably get one for around $20 or less. My supplier retails them for just under $18 Here is a pic of one.


Well, I was looking into it elsewhere, and it suggested I run a test to make sure the unit was bad and it wasn’t the wiring. How hard is it to do this test? How much does the unit cost? Could I get a shop to do it for a couple bucks? How much would I expect to pay an honest mechanic to check/fix this?

Also, I want to take a moment to thank you for your help.

I usually check them with my scanner. With the engine running, I can see the speed sensor signal RPM’s. In fact I had one a couple of weeks ago which was reading 13,000 RPM’s. You can also wiggle wires while monitoring it on a scanner. The scanner, to me is the easiest and fastest way to check it. I dont know where you live so I cant really tell you how much you are going to pay.


Portland, OR. Just curious how difficult it would be. Want an idea when they quote me labor.

Not difficult at all, remove electrical connector, remove 1 bolt, take pair of pliers, lightly grip outside of sensor, twist and wiggle while you pull the sensor out. With a dab of ATF or motor oil, lubricate “O” ring on new sensor, push it in and reinstall bolt. Plug in electrical connector.

Dont know the labor rates out there in OR. But call around. My cost around here would be $47.50 + parts.


I found a transmission shop who offered a free diagnostic. They hooked it up their machine and did a road test and came away with codes claiming it’s the TCM module, and they think it will require chasis electrical (which they don’t do). They referred me to a couple different places, but I wonder, since this is completely different from the code I got, if they are trying to scam me. Are they in cahoots with these other shops? And how much would I expect to pay to get this fixed?

And the two codes they recieved were u0101 & U0155.

I just posted something to your exact problem moments ago, but I have a 2004 Mazda 3. my problem is the exact problem…incredible. I’ve had a problem trying to find the problem since it doesn’t appear as much when I did a Google search. After much research I found out that it was the Turbine Speed sensor. I just replaced it over the weekend with my neighbor who’s a mechanic, after I read instructions on how it’s replaced. Since it didn’t sound complicated I figured my neighbor could do it. After all was done the problem was still not fixed. I am wondering if the problem could have gotten worse since I didn’t fix it immediately and drove with the problem for quite some time. I finally decided to do something when the light refused to come off even when turned the car off and on. To make matters worse what really scared me was when I would put the car in reverse the car jumped and made a horrible indescribable sound. I am hoping someone at car talk can help. I am going to go Autozone and check the codes see if I get the same one. It was so long ago that I can’t remember the code they gave me a while back. I am also going to look in to the codes your Tranny Shop gave you (u0101 & U0155.) I’d like to be well informed before I have to pay the $95 diagnostic fee the dealer charges. they say they will charge me the $95 fee whether they fix it or not. I think that’s not fair, if you’re going to do the work with them they should at least remove the fee. I would understand if I weren’t getting the job done there then they should definitely charge me the fee but if I am I shouldn’t be, but that’s just me. Apparently Mazda had some electrical problems with all their 2004 models. I hope this helps you somehow and I hope I can find some help from your thread.

I just wanted to add, that the dealer part for a Turbine speed sensor was $80 and auto zone wanted $107.

Well, to followup how this all got resolved. I called around, and every single auto shop charged at least $100 just for diagnostic, as it was very labor intensive. Most also told me that if it was the TCM, they’d send me to the dealer. The dealer was $115, so I figured, since I may have to go to them anyway, that they were the best option. They found out it was…

The Turbine sensor, and for them to replace it cost $200, but I just didn’t care anymore and wanted it resolved.

Did you replace the cable connected to the turbine sensor? Sometimes that can be the problem instead of the sensor itself. Also, if your engine light is still coming on, take to Autozone or Schucks, as they both run codes for free.

Or use the Mechanic resource they offer here. I just had something else go wrong, and found a great mechanic through them.

Thank you so much for all your help, all the information here has been very useful. I went to Auto Zone last night and found out that the code error was still the same P0715 (Turbine Speed Sensor Malfunction). The guy at Auto Zone told me had I checked the relays or fuses before I replaced the Speed sensor. I commented that I hadn’t. He said I should have done that first before I replaced the sensor. I spent $85 on the part and $30 for mechanic labor. All this morning I was trying to figure out how that piece is connected, if it was directly attached to the tranny or was there a cord/cable that connected/feed the information to the tranny, well you just answered that question.
I am going to use the Mechanic source now.
I am going to take some time out to take it to the dealer, i don’t think i can get around it, electrical problems are tough enough to pinpoint that I rather they rack their brains out.