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22 Bar Harbor Road
Ellsworth, ME 04605

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What Does This Blue Light on My Subaru Dashboard Mean? | Subaru Temperature Gauge | Subaru Dashboard Lights

Referred to as the "Coolant Temperature Low Indicator Light or the Coolant Temperature High Warning Light" in the Subaru Owner's Manual, this light will come on whenever you start your Subaru vehicle. Upon startup, your vehicle is preforming a temperature check. For the system check, this indicator light/warning light illuminates in RED for approximately 2 seconds when the ignition switch is turned to the "ON" position. After that, this indicator light/warning light changes to BLUE and maintains illumination in BLUE. This BLUE illuminated light turns off when the engine is warmed up sufficiently.

The blue light will stay on until the engine has reached optimal operational temperature. While you can still drive the vehicle safely with this light on, it is best to wait until the blue light has turned off. The light should only stay on for a minute or two, unless it is extremely cold outside, then it may take a minute or so longer to go out.

Aaron Hubbard, responding to this question on Quora.com explains why even modern vehicles need to be warmed up:
     "You don't have to sit in the driveway and let it warm up, but you shouldn't be driving very hard until the engine is up to normal operating temperature.  That means not using the accelerator much, and not revving the engine very high.  If it's a manual, take it easy on the shifting as well.  The blue light is a replacement for the traditional temperature gauge...which probably got attention from very few people anyway.

     "The reason that you need to let even modern cars warm up is that all the lubricants need to come up to operating temperature before they are their right viscosity.  Cold oil is not going to keep your engine or gearbox lubricated well enough to prevent damage when operating at full speed."

Brian Levin, Sr. adds:
     "It's no different than a temperature gauge, but Subaru opted for the mpg gauge and went with lights for the temperature.  Doesn't change the need to let the car warm up before driving HARD, but not necessarily before driving period."

What If the Temperature Gauge is Red?

After turning the ignition switch to the "ON" position, if this indicator light/warning light behaves under any of the following conditions, the electrical system may be malfunctioning. Contact Stanley Subaru's Service Center at 800-439-8989 immediately for an inspection:

   -It remains blinking in RED.
   -It remains illuminated in RED for more than 2 seconds.
   -It remains blinking in RED and BLUE alternately.

While driving, if this indicator light/warning light behaves under any of the following conditions, take the specified appropriate measure listed below:

   -Blinking in RED:
      Decelerate the vehicle. After the blinking RED light turns off, you can drive the vehicle normally.
   -Illuminated in RED:
      Safely stop the vehicle as soon as possible, and refer to the emergency steps for the case of engine overheating.
      After that, have the system checked by Stanley Subaru or the nearest Subaru Service Center.
   -Blinking in RED and BLUE alternately:
       The electrical system may be malfunctioning. Contact Stanley Subaru for an inspection.

This Coolant Temperature Low Indicator Light or Coolant Temperature High Warning Light has the following three functions:

1. Illumination in BLUE indicates insufficient warming up of the engine.
2. Blinking in RED indicates that the engine is close to overheating.
3. Illumination in RED indicates overheating condition of the engine.

If the engine coolant temperature increases over the specified range, the indicator light/warning light blinks in RED. At this time, decelerate the vehicle. After the blinking RED light turns off, you can drive the vehicle normally. However, if the indicator light/warning light often blinks in RED, the electrical system may be malfunctioning. Contact Stanley Subaru Service Center for an inspection.

If the engine coolant temperature increases further, the indicator light/warning light illuminates RED continuously.  At this time the engine may be overheating. Safely stop the vehicle as soon as possible, and refer to the emergency steps for the case of engine overheating in your Subaru Owner's Manual. ("Engine Overheating" 9-12.)

[UPDATE: Need to manage overheating? We have details here. Were you looking for why your lights are still on? Check out our post here.]

For more information on Subaru Dashboard Lights and Symbols, check out "What Does This Light Mean on my Subaru Dashboard?" or contact us at 800-439-8989.

1.  Quora.com Discussion "Subaru Outback Blue Light for Engine is Cold" and "Should I warm up the car until that goes out":  http://www.quora.com/Subaru/In-the-2011-Outback-there-is-a-blue-light-for-engine-is-cold-Should-I-warm-up-the-car-until-that-goes-out-before-I-drive-it.
2. Subaru Owner's Manual: 2011 Outback/Legacy. Subaru Quick Reference Guides and Complete Subaru Owner's Manuals are available on www.Subaru.com under For Owners>>Resources>>Get Your Owner's Manual. I referenced the 2011 Outback manual due to its relevancy to the question posted on Quora.com and the frequency of questions about this specific model year.

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Hi my 2012 subaru legacy with key on the temp light flashes blue and red alternately along with other cluster lights flashing no ignition car wont turn over ,ignition switch bad?
Post Follow Up
Jeanne Dennison
With ignition issues, it can be tricky to know what is wrong without seeing the vehicle. It is best to take your Legacy to an authorized Subaru Service Center to have a computerized diagnostic completed. If you are local to the Ellsworth area, give us a call at 207-667-4641 and we'd be happy to take a look at it for you. If you are not local to the area, visit your local Subaru dealer to have the ignition inspected. 
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