2019 Subaru Outback - Parasitic Battery Drain

Question

If I don't drive my Outback for 48 hours, the battery is completely dead. I've already had the battery replaced three times under warranty, and the dealership keeps saying the alternator is charging fine. They tell me I'm 'not driving it enough' to keep it charged.

I've checked for lights left on and the hatch is definitely closed. I did a draw test with my multimeter and I'm seeing about 150mA of draw after the car sits for an hour, which seems way too high. Usually, it should be under 50mA.

NightShiftNate · Answer

✅ Confirmed fix: This is a very common issue on 2016-2020 Outbacks and Ascents. The Starlink Telematics Module (DCM) gets stuck in a loop trying to search for a 3G signal that no longer exists because the towers were decommissioned.

Because it can't find a signal, it never goes to 'sleep' and stays on the CAN bus, pulling about 100-200mA constantly. I pulled fuse #15 in the engine bay and the draw dropped to 20mA. The permanent fix is having the dealer bypass the DCM or install the updated 4G module. If you don't use Starlink, you can just leave the fuse out, but your front speakers might not work because the audio passes through that module.

CoolantKai · Answer

Check the rear hatch latch sensor. Sometimes they fail in a way that the BCM thinks the hatch is open, which keeps the interior CAN bus awake even if the lights are off. Try lubricating the latch mechanism and see if the draw drops.

2019 Subaru Outback - Parasitic Battery Drain

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