Electric power steering assist

If the EPS is working properly you won't really feel anything other than being able to steer the car. A quick test would be to turn the steering wheel while the car is setting still. If you can turn it easily with one hand from lock to lock the steering is working. If on the other hand you need to brace yourself and fight with both hands the EPS isn't working. However if it wasn't working I would expect a few codes to show during the scan and the steering would be heavy while driving plus the MDPS warning light would be on to tell you the system has a problem. That light should come on when you first turn on the key during the bulb test. Then go out when you start the engine. I've attached the electrical schematic. It shows 2 fuses that power the system, the MPDS 10 amp fuse in the box at the end of the dash and the 80 amp fuse in the fuse box under the hood as part of the multi-fuse. You could check those, however the steering wheel test will likely show you more.

They look fine, when those fail they are very apparent as they create a mess. However testing it isn't hard, you just need a test light and find the orange power lead that feeds the power steering motor and test the back side of it for power. However if there was no power to the unit even steering it in motion would be like steering an old manual steering car.

Check the same power supply as above but being it was intermittent and then fully stopped I would suspect that the EPS unit itself is the failure item. Those are not all that difficult to change out if you have the tools. You remove the trim covers then unbolt the column and release the pinch bolts on both sides of the module. Unplug the electrical connection and reverse to install the replacement. Then you use a scan tool to reset the steering angle sensor and test the modules operation.

It is usually mounted on the steering assist assembly itself as a self contained unit. On yours it's the box in the top left of the picture.