Outside temperature appears to be off how can I check

Check it with a second thermometer if there isn't a calibration procedure in the op manual.

There's a lot of standard deviation with these devices. Look at how you can drive down the street and see a lot of businesses with thermometer readings and they are all different. I would trust your cell phone over all of these sources. Why are you so concerned about the car's reading and demanding absolute accuracy? I'm sorry, but, you're expecting too much, it's not like you're in a hospital surgical room. The outside temperature is a pretty good estimate and I would not get too excited about it. I would pay more attention to my fuel-efficiency and how well the car drives and your overall enjoyment of the car and long term service.

Mark, I am not concerned about 1 or 2 degrees or even 5 or 10 but when I pay cash for an new 2015 car and it is 101 degrees outside and it says 70 something isn't working. I purchased my Subaru Limited with gas efficiency as the number one criteria and it only has 900 miles on it. Not sure where you got the "absolute accuracy" criteria.

rigilsp- yes, sorry, but, it probably would have changed my answer if you had originally stated that your temp gauge was reading 70 degrees when it was 100 degrees outside.

If your car is sitting in traffic or has been sitting in the sun the reading can be off. Once on the road the reading should be +/- 1 degree though. Getting the sensor wet will also cause a low reading.

Subaru like a number of cars have the temperature sensor down low behind the front bumper. While it gets a good flow of air, the air it gets is the air sitting just above the road surface and is naturally hotter. A better location that some Fords have is underneath the outside rear view mirror. Much higher off the ground and more representative of the temperature of the bulk of the air. However, excluding the deviation caused by unrepresentative placement of the sensor, it is inexcusable if the accuracy of the actual sensor is worse than 0.5C.

These temp sensors are just thermistors, many of them 3k @25C such as my '04 Forester. They are not incredibly accurate instruments, they usually have a tolerance of +/- 5%-10% from nominal, but they work fine for this non-vital task. Your low reading would indicate that the measurement circuit "sees" more resistance than it should for the design 3k (at 25degC) NTC thermistor -- by a good amount like a couple hundred Ohms given the temp error, but not by so much that there's a complete break in the wire or anything...probably just a bit of extra contact resistance at the sensor's plug (likely under front grille, can get dirt or water easily).

I’m going through the same thing with my 2015 base model Impreza. It’s 81F and it reads 56F. Did anyone find an answer?

2008 WRX here. My temp reading was low by about 15 degrees. It seemed to be having an impact on how cold the AC would blow although I can't confirm that. It was 85 out, temp was reading 69..ac was pretty weak. I simply disconnected the sensor wiring and sprayed a little deoxit D5 inside and worked the connector on and of a few times to clean it. Working perfectly now...accurate to within a degree or two.

When I took it in to the dealer they said to not worry about it, not really a problem. In winter here in the mountains making my veterinary house calls, I’ve trusted my ‘16 Forester to warn me when the wet roads may be icy. Now, whatever the lowest temp is, even now in the summer, it stays what it is in the morning most of the day even when it’s over 20 degrees higher. Sometimes it goes up, can't depend on it. Is it fixable away from the dealer?

I’ve had this problem since taking delivery of my 2018 Outback. It can be as much as 40 degrees higher or lower than the actual outside temperature and it will stay locked on this extremely inaccurate temperature ALL DAY. They replaced the sensor, the wiring harness and the chip/board. None of which fixed the problem. It really upsets me when dealers guess at stuff and have no clue how to actually fix anything.

My 2018 Forester was always 2ºF off, no big deal I just took it into account. My 2021 Forester is always 4ºF off; I'd like to have it recalibrated, not sure whether I can do that myself.

Mine is definitely not 2-4 degrees off. It can be off 30 to 40 degrees depending on the outside temp. I keep it garaged. In the winter my garage is about 60 and this Outback will stay locked at 60 for hours even when it is 30 degrees outside. In the summer, a couple of weeks ago in fact, it was 95 outside and 75 in my garage. The car said it was 75 degrees the entire day of driving. They have no idea how to fix this, as they supposedly changed out everything associated with the outside ambient temp indication, including the wiring harness. I’m fairly certain they wasted tons of time and money, as I believe it is a software glitch.

I wish someone found the answer to this. Mine was reading -22° yesterday when it was 78° out. I was having a hard time getting the ac to work well, it would not get cold, I had to turn it on and off and play with the temp setting to get it to work. We replaced the sensor and it didn’t help at all.

If you could all PLEASE contact Subaru of America directly, we could probably get this fixed. Dealers just guess and experiment, and honestly this isn’t their fault. Subaru NEEDS to fix this. I have a case agent or whatever they are. Subaru is saying they are hearing about this problem. So, they are either flat out lying or very few people are complaining. Perhaps it’s just me, but I’m under the impression that most subaru owners have a B personality. I admit that I am a AA. I want everything done right the first time, done immediately, I can’t deal with incompetence, etc. I’m guessing many Subaru owners just don’t care or even notice. One of my biggest issues is the fact that I own a 2010 Volvo and a 2001 Toyota 4Runner and they both shown EXTREMELY accurate outside temps after immediately starting them. They are both literally the same as what my phone states. I shouldn’t have to pick up my phone, WHILE DRIVING, to see the outside temperature!!!

My outside temp showed as 49 degrees in the garage, and didn't budge when we went to lunch. Turned on the AC after out a while, and temp gradually climbed to what it should be. I'll post again if it continues to do it.