Ok, here we go. On different occasions my 2008 Mazda 3 will not crank sometimes. The immobilier light is not flashing, the fuel gauge is on full, the mileage is displaying on cluster. All of this is happening prior to inserting the key. Now, it has been to Mazda 3 times. Each time they put the vehicle into self test mode, the tech hears a "click" and then the vehicle resumes operation as normal with all things working normally. The car may go a week, a month, or 2 days until the issue arises again. Here's what we know it is not;

The keys
The battery
The keyless remote

Again, the car functions normally until something disables it. Once that issue occurs, the immobilizer light will NOT be flashing prior to inserting a key, the fuel gauge remains on full whether the engine is on or not, and the mileage displays whether the engine is on or not. Once you get in the car and see these issues, there is no need to even try and start the car because it most definitely will NOT. The vehicle has to be towed to Mazda, and they have to hook the car to a computer, put the car in "self test", and then it will "click", and resume normal operation at that point.

Here is the BEST part. They do not know why it is happening. So, if there are any Mazda Techs on here that have seen this issue before, and know of a way to either fix the problem, or bypass the immobilizer so this issue will not happen again, PLEASE let me know, or call VIC BAILEY MADZDA in Spartanburg South Carolina 864-582-1200 (ask for service department), and once you reach the service department, ask for Ed. Tell him you are calling in regards to the blue Mazda owned by James Bolton. Because, the car is there right now! I purchased this car for my 16 year old daughter, and it is HIGHLY unreliable at this point. I am scared to let her go anywhere in it, in fear of her being stranded somewhere.

 

Each time you say the gas guage is on full, is the tank full, or just displays full?

 

Have they replaced anything? Check this link. I don't have a mazda 3 manual, but look at this if the dealer hasn't done anything other than reset it.
Ford Workshop Manuals-Galaxy 2000.75 (04.2000-02.2006)-Generic Electronic Modu