2019 Subaru Outback - Parasitic Battery Drain - Dead Every Morning

Question

I'm on my third battery in two years. If I leave the car overnight, I have to jump-start it in the morning. I've taken it to the dealer twice and they say the charging system is fine and the battery tests good.

I did a parasitic draw test and I'm seeing a 350mA draw after the car has timed out (waited 45 mins with doors locked). If I pull the DCM fuse, the draw drops to 20mA. But without that fuse, I lose my radio and Starlink features. What gives?

BackyardBilly · Accepted Answer

✅ Confirmed fix: This is a known issue with the Data Communication Module (DCM) on 2016-2020 Subarus. The module stays awake trying to find a 3G signal that no longer exists (since the 3G sunset), which kills the battery. The fix is a firmware update to the DCM or replacing the module with a newer 4G LTE version. Subaru has a service program for this under TSB 15-240-19R.

MountainMechMo · Answer

Check your tailgate latch. If the rear hatch isn't fully seated or the sensor is dirty, the Body Integrated Unit (BIU) won't enter sleep mode, keeping the CAN bus active and draining about 250-400mA continuously.

2019 Subaru Outback - Parasitic Battery Drain - Dead Every Morning

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