Need help, 04 Mazda3 Trans slams in reverse
 

So I have an 04 Mazda 3, and whenever I go to drive it and shift into reverse, it slams into gear and makes a loud clunk. The AT light is on, but when the car warms up and/or is driven for a bit the light goes off and the problem disappears. I've put it on a code reader and it's throwing the code for the Bank 1 Solenoid but I'm not 100% sure that's the problem being that I can't find anyone else on the internet with the same problem. Any insight would be helpful and much appreciated.
* Edit; It also shifts perfectly fine into any forward gears, never had any problems there but the reverse is what gets me. If anyone knows what the problem is and knows how to fix it and where to get the part(s) without costing me my extremeties, please do tell. Many thanks.

Take it to Mazda for a code check, aftermarket scanners aren't as acurate or complete as Mazda's tester.

Check the fluid colour, level & smell. When both hot & cold, in Park with engine running.

Checked yesterday, fluid is only a tad low and light brown color. Ive been having this problem for a few months now, had it checked by a mechanic and was told that being it was my reversegear it isn't a major problem? I think my next step after having it checked over again is going to be to flush the tranny.

Do not under any circumstances flush your transmission. Transmission flush procedures are often very harmful to transmissions and can lead to premature failure. Your best bet for servicing your transmission would be to drain it, refill it, drive it for say a week, and then repeat twice more.

Flushing is fine.

Yup, that's why virtually every manufacturer in the world actively recommends against flushing. Sorry, flushing is bad for transmissions.

Soooo does anybody have an idea as to what the underlying problem might be or what a good step in the right direction would be? My mechanic also says flushes aren't necessarily the greatest idea BUT it may help clear the problem up.

Tcm
 

I've been having the same issue for some time. As far as I can tell because of the intermittent nature of the issue it has to be electronic. The actual relays in the tranny aren't currently accessible with the equipment I have so I have a new TCM coming in the mail tomorrow or Thursday. Will update with results.

TCM replacement
 

So it's not the easiest job in the world, but replacing my TCM at this time has solved the issue.