AT light on Mazda 3


Asked by Oct 07, 2017 at 08:28 AM about the 2005 Mazda MAZDA3 S Hatchback

Question type: Maintenance & Repair

(copied from  my post yesterday) My AT warning light has come on twice in the past month. A 2005 Mazda 3 Hatchback 97,000 miles. The first time, it felt like the gear had slipped out when I drove out of car lot. I parked car and turned it off and AT light disappeared when I restarted. No problems for a month until today. The AT light came on today and the manual M part of transmission would not go from 1, 2,3 or 4 but the D auto transmission worked fine. I parked and turned off car, light and problem disappeared upon restart. I'm hoping it is a fluid level, sensor or computer issue. I I will check fluid level and disconnect battery so that computer can "reset." If it happens again, I'm going to a tranny shop. Any ideas/input appreciated.

16 Answers


Pull the codes before you clear them.

9 people found this helpful.

Both times the AT light disappeared after turning off engine. So I would have to go directly to a code reader while the motor is still running. The mechanic picked up nothing yesterday as the motor was already off . I already disconnected negative battery terminal and everything is fine now. Also, tranny fluid is pinkish red and at correct level. From what I've read and analyzed here and on other forums, I'm in better shape than a lot of others with tranny issues. Mine is likely or hopefully something electrical rather than mechanical. Another thing I'm trying to do is to keep it in Auto D and not use the M so much. It's better to wear brakes than potentially damage tranny.

6 people found this helpful.

Hey there, did you ever figure it out? My 2007 Mazda3 has started doing the same thing.

9 people found this helpful.

NO. It has been a problem for 10 months on and off. It hasn't gotten worse so I have learned to live with it.

4 people found this helpful.

Hey; the problem mentioned has just started on my car; what is the suggestions of you?

8 people found this helpful.

Check your input and output speed sensors. Mine was doing the same thing and that was my issue.

2 people found this helpful.

I bought a cheap input speed sensor 6 months ago but never installed it. Car still does same thing, but it goes away for a month if replace a quart of dirty fluid and add a clean qt. This is easier to do than fool with the input sensor. Next time I'm going to add some Lubegard additive. Universal type # 60902. I suspect that my problem is a solenoid valve that gets stuck. Once car is warmed up, metal expands in valve and it works fine. Fresh fluids help this.

6 people found this helpful.

Similar problem. 2007 Automatic Mazda3 Hatchback 2.3L Driving to work one day and suddenly car jerks and shifts down from 5th to 3rd. Yellow AT light is on and car will not shift up from 3rd, runs at high rpms. Pull over and shut off car. Start back up and problem goes away... until I’m driving home. Same symptoms. This happens for days. First fix I try is replacing tranny fluid and filter. No change as problem happens again next day. Next fix is I replace the speed sensor that’s located on top of the tranny (under the air filter tray). Easy to fix. Car worked fine for 2 weeks (~600 miles). Today, after picking up lunch, same problem occurs. AT light is on and won’t shift above 3rd. The next fix I’m going to try is the TCM (Trasmission Control Module). It’s definitely pricier ($600) but still cheaper than a new car or even a new tranny.

15 people found this helpful.

If your Mazda 3 shifts gears from 5 to 3 randomly, the AT light comes on flashing with the engine light, then the AT light goes off in about 3 miles, followed by the engine light in about 30 like everything is fine, it's very likely the Transmission Control Module. The TCMs on Mazdas 3s are pron to overheating due to their proximity to the engine and crap out after 40k miles or so.

9 people found this helpful.

I must have been really lucky because mine didn’t crap out until 166k miles. But I have heard, in other forums, this happening when the car is still new (<30k miles). Apparently they’ve gone thru 5 versions of the TCM as the latest has a part number that ends in ‘E’ where the previous started with ‘A’ and went thru the letters until ‘E’. For those wondering, the latest as of January 25th, 2019, the part number for a TCM for 2007 Automatic Mazda3 2.3L is L34T-18-9E1E.

11 people found this helpful.

I had check this problem for my custom by scancar and i found a foult... On 3 and 4 gear ...

2 people found this helpful.

At means automatic transmission. Add tranny fluid. Mine did the same, shifting hard, resets when shut off. The plug to add is under the air box and more less under the battery box.

4 people found this helpful.

i have the same problem with my 05 mazda 3i sedan . FIrst i noticed the acceleration from stop was way slow than the car started shifting way to late than jerking than the At light popped up and 2 weeks later my car wont even make it up the driveway. i have not had much time in the last week to take the time to look at it more . sounds like you guys are all having a problem pretty close to mine any help would be great . thanks guys !

4 people found this helpful.

I have same problem my top tronic don't work as well a nd it stays on 3rd gear

2 people found this helpful.

Don't laugh ... Have you tried spraying off your radiator with a high pressure sprayer? If it gets clogged up with bugs and whatnot, from alot of freeway travel, it is a great possibility! It will clog up the tranny's cooling system....

2 people found this helpful.

my 2003 mazda 3 2.ol bogs and the lighy flickers when going 100km and i got a code p0706 tr switch it has a new transmission range switch does any body know what the cause is

1 people found this helpful.

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