This is a Lifespan Fitness Treadmill if I'm not mistaken. Sometimes it can be difficult to tell from the common name since they are often shared by different manufacturers. So if that is incorrect, please let me know.
The Lifespan Fitness Traction II has a specific error format. It is E followed by two numbers - E01, E02, E03, E04, E05, and E06.
And it sounds like that is not what you are seeing displayed. So any information you have about what exactly you were doing when it failed incline, speed, etc, might help us to figure that out.
The only part of what it is displaying that resembles a valid error is the 04 - E04 would represent a problem with the incline motor specifically, an "incline self-learning" error. To check that, . Check connection of VR wire of incline motor. If improperly connected, reconnect VR and make it firm. 2. Check to see if AC wire of motor is properly connected, and if the AC wire of the motor is inserted properly with correct sign on control board. 3. Check connection line of motor to see if it is destroyed, exchange it or incline motor. And press “learning” button of bottom control board to relearn upon completion of checks.
However, if you already know the incline isn't the problem or if you determine that by checking the incline motor, then I suspect it is the console itself that has failed. That's usually the case when an erroneous error is displayed.
I'm going to give you a link to the LifeSpan Fitness error code page - you do have the option of clicking on that page to send the error to customer support. Based on the information you've provided to me, I don't think that will result in anything useful, but in case you want to try it before dumping money into a repair, here is the page:
The errors listed on that page are the combined errors for all models - yours is supposed to only have the E01-E07 error, but E9 errors are possible, although they are not documented outside of the company.