Key fob not detected?

The "aftermarket remote start", did this problem happen ever since it was installed? Let's check the fuse #f121 which runs the system here is a guide to help and I have included the fuse location in the diagrams below. See if the fuse has power as well.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

I have seen the keyless ignition node module go out and cause this problem, but to be sure we should do a CAN scan. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is how to replace the keyless ignition node module in case a code comes up for it. Check out the images (below). Please upload pictures or videos in your response to the problem so we can see what's going on.

The description sounds like the fob failed but I would try to erase and program it back in because even a dead fob should still start the car when it's held up to the button. At that point the reader in the button reads the RFID tag in the fob and tells it if you have a valid fob. Because that also isn't working, I would start there. I would also look at the remote start and see how they bypassed the fob reading to start the engine. Depending on how that works it might have failed and is now blocking the OE reader from actually working. Wouldn't be the first time I have seen that. Did a DEI remote start a couple months ago, it had an internal failure and while it would still start the engine the car wouldn't start with the button. Ended up removing the remote start and programming the original fobs back in to repair it.

I would use a key reader to verify your OE fobs are working and to read the vehicles PIN. I still think it's likely something in the aftermarket unit because they tend to cause issues like this when they start to fail. However, you really need a scan tool to see what the receiver in the vehicle is seeing and I would look up how that remote start was connected and how they bypassed the OE SKIM module to allow it to work.
As for it preventing it from starting, at the moment it sounds like the OE fob isn't controlling anything but the door locks. It isn't reading the fobs security at all. A quick test would be to put the OE fobs in a metal box or RF shield bag and see what the vehicle does. Do you have more than one OE fob? At the moment I'm wondering if they didn't remove the RFID from the fob and installed it where the reader in the push button can read it to allow the remote start to work.

4 years is pretty good for an aftermarket unit. However, it's like anything else, it can fail. I've removed a lot of them over the years because of them causing issues. Many of the ones I've removed were installed by "professionals" who used twisted wires, scotch locks, wire nuts and electrical tape and the failures were due to the unit failing or their "high quality" wiring failing in some way. In your case you might want to just grab another fob and program it into the vehicle, which would tell you a lot. If it programs in and works properly you now know the fob you have is bad. If it acts the same as the fob you have then you need to dig into the car's systems. Worst case is you end up removing the remote start to get both fobs to work and now have 2 fobs.

STEVE W. Is one of our best! Please let us know what happens.