I have a 2019 Outback as well. I just went through some battery dying issues. Took it to the dealership, they said that the Onstar module (after 2-3 years) will start to malfunction and create a parasitic drain.
The only fixes they have (as of a couple weeks ago) was to
a) buy a new module (which are on back order because a number of peeps are having this problem) -- which will eventually break because they haven't reengineered it.
b) disconnect the Onstar module via a circuit (my tweeters are on the same circuit, so I'd lose them)
c) Open up the center console and only disconnect the Onstar module.
I opted for C (which I was charged an hour of labor for).
The tech there said to check back in every few months to see if Subaru puts out a new module that fixes the issue.
Edit: The tech told me the Onstar module was a specific issue with 2019 Outback/Legacy, and that 2018 and back doesn't have that problem and in 2020 they redesigned the whole model, so the newer ones don't have that issue.
I have the same issue, seemingly, with my 2017 Outback. My battery kept dying for which I got a lot of run around from the dealer (gaslighting about keyless entry drains it if the key is too close to the car, etc.) Eventually I found a Reddit post about the DCM (Starlink) module, removed this fuse, and it hasn't died since. It sounds like it wakes up in the middle of the night to do something and thereby drains the battery, so whenever they test at the dealer for extra drain, they find nothing. Having that fuse out kills some speakers and the mic too, so it's a kind of annoying solution. I have not gone back to complain again recently though, so maybe they can do whatever it is they did for you. I saw some posts about wiring it to another circuit that's off when the car is off, but I am not confident doing that myself.
Starlink! (not Onstar) ... I'm not subscribed myself so I can never remember the name.
> Having that fuse out kills some speakers and the mic too, so it's a kind of annoying solution.
That's exactly why I didn't choose that option.
One thing I'll mention about the center console solution (which I'm having trouble confirming), when I was driving home I thought the sound from the speakers was much quieter. I tried zoning the music to the quiet speakers and there was little to no sound coming out.
I took it back and they took the console apart and reset everything and then it "just started to work". The tech seemed as baffled as me, he was frustrated he couldn't tell me why it started working.
All that's to say YMMV.
One was a PEBCAK that I personally consider a design flaw: the rear gate light switch is on the ceiling at the opening of the gate (on our 2016), and the “on” position is activated by moving the switch outwards, ie towards the back of the vehicle. It had been inadvertently dragged into “on” position while unloading bikes, rafts and other outdoor gear, and then killed the battery while we were out for a couple days.
Didn’t realize this was happening until returning to a drained battery on two occasions, and then observing the effect later while doing some garden work, when I finally connected the dots. I’ve since duct taped it into the “off” position.
