2017 subaru Forester, 2018 Impreza, 2018 Outback. On all three cars, leaving the key in the ignition with car off resulted in a dead battery. Happened only once with each car because they each had a different driver who didn’t do it anymore.
Good, they learned after the first time.
There a number of reasons why this isn’t a good idea even without considering the dead battery consequence…
2 Likes
When the key is removed the computers figure not much is gonna happen so they power down into a low energy mode and wait. There’s a gadget in the ignition switch that signals the computer when the key’s in. Leaving the key in keeps the computer’s powered up, and that indeed could run down the battery overnight. In an ideal world I guess the computer would figure out it wasn’t needed and go into low energy mode anyway, but I guess adding that function was considered low priority.
Wow 3 different people, 3 different cars, same mentality. Is there actually a point here?
1 Like
“Hide your keys under the mat, do not leave it in an ignition switch” ? 
Thanks for the info. For the record, in none of the cases was the key in the ignition longer than an hour so I thought it might be a problem with Subaru batteries, particularly in cold weather.
As for the other respondents…get a life. Your snarky, condescending replies were unnecessary.
That’s news to me that key-in is enough to activate enough electrical circuits that it can drain a battery. I wonder if that info is in the owners manual for these vehicles. I would want to know that about a car I own.
My worst key-in experience was in 1996. The switch on my 1983 Corolla wagon was very tricky and it worked better if I just left the key in. One Saturday I drained the coolant. That night my neighbor called - he’d heard on his police scanner that someone driving a car like mine was being chased. I went and looked and my car was gone! The car quit, the kid ran, the police got him and my car was towed to the station. When I got it back the head gasket was shot and the heater control valve had melted. I replaced the gasket and valve and the car ran OK despite the severe overheating. I submitted an accounting of my expenses to the court.
Fast forward to fall of 2018, 22 years later. I got a check for $403.24, crime victim compensation, thanks to the WI corrections and court systems.
I discovered a few years ago that leaving the headlight switch on in my 2010 Kia Forte and turning the key to ON turns the lights on and turning the key to OFF turns the lights OFF as expected. If the key is left in the switch the parking lights stay on! This is for some reason identified as the “Battery Saving Feature” in the manual.
I have a 2010 Outback. If I leave the light switch in Auto (turns on when it gets dark) it can be an issue. I pulled into my garage one night and the garage door opener light made the car think it was light out so the car lights went out. Of course the garage light stays on for 10 minutes. Long enough for me to go in the house and go about my routine. But when the garage door opener light eventually goes out the car turns the lights back on if the key is in the ignition (even if the ignition is in the off position). I see no issue leaving keys in a car in a locked garage. Now I turn the light switch on and off manually.
22 years? Did the court system provide an explanation why it took that long for the wheels of justice to deliver that crime-compensation check? I wonder, did they have to wait for the perp to pony up the loot first? If so, I wonder what motivated them to finally pay up after 22 years?
I’d be surprised if leaving the key in the ignition for an hour, in “off”, would drain the battery so much it wouldn’t crank the engine. Overnight, maybe, and 24 hours, likely. But not just one hour. I think there must be a battery/connections/starter issue. My theory doesn’t explain why it happened with nearly new cars is the problem. Subaru’s are not as common as the other major brands here in San Jose, but were very popular in Colorado where I used to live, b/c they were (at that time at least) designed to handle winter ski trips without complaint. And they did, my parents had one. Being able to crank the engine in the morning at 0-10 deg F to get to the slopes is an important part of a winter ski trip. If they couldn’t handle that, nobody would have bought them. At this point I guess the key-left-in-the-ignition thing remains a mystery. There may be some software design issue w/that vehicle even Subaru isn’t aware of. They probably don’t test for current drain with the key left in the ignition. That’s something a shop could easily do though.