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2019 Premium w/eyesight
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71 Posts
Discussion Starter #1
Hi, my blue temperature light goes off a couple minutes after starting. It can’t mean that the engine is fully heated because the heat is still cold. What exactly does the blue light going off signify? Is mine defective do you think?
 

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2019 Convenience / EyeSight CVT
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52 Posts
The blue light is monitoring the coolant temperature. On my car it always blinks out at 50C (122F) while doing a slow drive for a couple of blocks.
 

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2019 Premium w/eyesight
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71 Posts
Discussion Starter #3
I don’t understand why they make it shut off at a low temperature like that though. Shouldn’t it stay on until normal operating temp is reached ?
 

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2019 Touring CVT
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291 Posts
I also noticed how quickly the blue light goes out. My 2015 Forester did not turn off the blue light as quickly. Also heat to the cabin is coming more quickly.
 

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2017 Forester XT Premium
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552 Posts
Mine goes out between 106 and 108 degrees fahrenheit every time, although during the sub zero winter days it did take longer, about 112 degrees on those days. Im easy on the gas until about 160 and then I drive normally. Doesnt take long.
 

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2017 Forester 2.5i MT
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288 Posts
The blue light is monitoring the coolant temperature. On my car it always blinks out at 50C (122F) while doing a slow drive for a couple of blocks.
The display on my '17 only gives me oil temps. Does the '19 give you coolant temps?
 

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2020 Forester Touring CVT7
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223 Posts
@Peja i did not see one but CVT temp regulated by Coolant temp .. and (if i remember correctly) if its over 10+ different from Coolant it suppose to trigger warning light
 

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2010 FXT slush-box
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661 Posts
You Tube videos

There is a nice video (using a heat camera) of a subaru turbo motor warming up. There was a big difference in warmup time for various engine components. The take home message for me is to wait several minutes AFTER the blue light turns off to get on the turbo. Probably not as important in NA and/or stock engines. I have noticed that in the winter my (modified) engine can knock if I get on the turbo right when the blue light turns off.

Jeff
 

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2019 Forester Sport Rubber band
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522 Posts
@Peja i did not see one but CVT temp regulated by Coolant temp .. and (if i remember correctly) if its over 10+ different from Coolant it suppose to trigger warning light
That is great information people need to know. In reality it's information most people will never know.
 

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2005 Forester EJ251
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107 Posts
I have an older subaru. Compared to other car engines, their coolant passages are small and the engine doesn't hold much coolant. It is designed to heat up fast to improve emissions. In your later Subaru it is possible the thermostat warms the engine first before allowing coolant to go to the heater core.
 

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2011 Forester 2.5X Manual w/ Ko'2
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93 Posts
My blue light always come off at 50C... Yes the air is still cold at that temp, your gauge is fine. A good heat start at about 80c, it takes a couple mins of drive after the blue light off.
Usually when the blue light is On you should wait before activating the heat because air will be cold and you will increase the engine warm up time (inefficient).
Also if I have the time to, I wait that my blue light goes off before driving the car. If I have no time I be very easy on the throttle until then.

Be careful, I've seen some post in here mentioning that when the light goes Off you can smash the Throttle, that is no true! 50c is way to low of a coolant to put engine at full load! 90c is the operating temp and will take couple mins of driving to get there. Your oil temp will take about 10-15 mins to get optimal (under normal driving warm weather, 25mins when extreme cold).
 

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2019 Forester Sport
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2,452 Posts
It is absolutely amazing what you can learn if you just read the manual:thumbsup:
 
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