Check Engine Light is on - What can be wrong???

Could be your MAF sensor. Mine was jerking like I was a new 5-spd driver. Took it in and they replaced my MAF under warranty. I have an Injen cai installed too. They didn't care. Maybe this could be your problem.

Would it still be replaced even if its past warranty? cause warranty is 50k

Go to autozone & get the codes scanned...guessing at what it could be without the codes isn't going to get you anywhere.

if you have an intake the wires to the maf sensor could have gotten severed. A look through this thread may help you too:

http://www.mazda3forums.com/index.php?topic=49413.0

If the car is out of warranty, they will still replace it - however you will pay for the part and labor.

Have Autozone scan the code so you know what's going on. They won't charge you for that either.

If it is refusing a 4th gear shift and illuminating the AT light more likely then not it is an issue with the transmision. My guess would be either a bad clutch pack or the valve body is dying.
-Matt

The code autozone gave me is P0715 < --- ANY INFO?

I know it says ... P0715 Input/Turbine Speed Sensor Circuit Malfunction but what exactly is that? and how do i get it fixed?

Sounds like the MAF sensor to me, but I dont have the codes memorized.

Anyone?

I have a similar problem actually, i came out of a parking lot and was accelerating and after i shifted into 2nd at about 2-4k rpm it felt like it had just redlined and then my check engine light came on, i took it to a local shop and had them scan it and they said MAF input high anyone know what exactly that means ?

Well, I just recently got an oil change, and now its not doing it anymore or hasn't (knock on wood) so I don't know what the heck is going on with mine anymore, if its the sensor I don't know what an oil change would of done to fix the problem!? I'm stumped! I have a 60k due but can't afford it ... so I got to do it in small parts, I think im gonna get fuel injectors cleaned first then do the flush coolant and transmission. Ahhh

There is a sensor that detects the speed of the torque converter. It isn't working properly, hence the code. Likely you are going to have to have it replaced. It also could be that the wiring is frayed and periodically shorting, but I would consider that a lot less likely. My guess is if it is a hall effect type sensor you are looking at $40-60 for the sensor plus whatever labor (I assume accessible from outside of the tranny, so like a half hour of labor to remove the belly pan and replace the sensor). I am not sure how the three's ECU works, but in a lot of cases if there is a turbine speed sensor it is used to determine when to lockup the torque converter and/or shift and/or what line pressure to use to preform the shift. I would highly recommend replacing it.

If I had a repair manual I could tell you exactly where it is and how to replace it. Without one I would need to be there working on the car to do it.
-Matt

Probably a dead tread but I've been having the same issue with my 3. Every so often the CEL will come on, the car'll drop out of 4th gear into 3rd and the "AT" light will pop up on the dash. I'll have to come to a complete stop for it to go back to normal but the CEL stays on. Just wondering if the problem was a bad sensor or if anyone knows what this is? Thanks. The car's an '05 AT

[quote author=anrkey99 link=topic=65054.msg2040066#msg2040066 date=1201891300]
Probably a dead tread but I've been having the same issue with my 3. Every so often the CEL will come on, the car'll drop out of 4th gear into 3rd and the "AT" light will pop up on the dash. I'll have to come to a complete stop for it to go back to normal but the CEL stays on. Just wondering if the problem was a bad sensor or if anyone knows what this is? Thanks. The car's an '05 AT
[/quote]

mine was the same symptom. just make sure you have the same code i had... P0715

i replaced the turbine speed sensor and it fixed the problem. its really easy to change. well.... i already have a aftermarket intake so its easier for me. just take off the intake and the sensor is right in the opening.

i bought the sensor from tiffany @ showcase and its less then $30 and she helped me get a diagram of where exactly the sensor is. =)

I have a 2006 Mz3i with an automatic, and the other day while driving home, my CEL and AT light both came on at the same time. There was no strange behavior or unusual sounds or revving, but I suddenly couldn't shift into first or fourth, and M mode doesn't work. The car starts in second gear now. Has anyone had this problem as well? I'll be taking the car to Autozone to have the code read - I really don't trust my dealership, and I'm hoping someone has some insight! Thanks.

nope, i have not heard of that specifically...either way, sounds like a dealership thing...under warranty I hope.
if you know a aamco place, they can also do warranty work (i think).
maybe if you refine your location a little, somebody can suggest a dealership you can trust.
ron tonkin in the NW,,Showcase in AZ...

[quote author=ingenius link=topic=65054.msg2046026#msg2046026 date=1202166903]
I have a 2006 Mz3i with an automatic, and the other day while driving home, my CEL and AT light both came on at the same time. There was no strange behavior or unusual sounds or revving, but I suddenly couldn't shift into first or fourth, and M mode doesn't work. The car starts in second gear now. Has anyone had this problem as well? I'll be taking the car to Autozone to have the code read - I really don't trust my dealership, and I'm hoping someone has some insight! Thanks.

[/quote]
I just read the whole thread and it sounds like you are having the same problem as everyone else. See if Autozone gives you the same CEL code as the other guys. If they do, problem solved. If not, check back in.