Question: While I was driving the other day, I noticed my rearview mirror turned blue for a while, but then later, it went away. A week or two later, I noticed it happened again. Why is my rearview mirror blue?
Answer: Your rearview mirror probably has a blue tint already, but because it’s a subtle tint, you may not have noticed. If you’ve ever experienced your rearview mirror turning blue while driving, you might wonder what causes this phenomenon. It’s not a bug—it’s a feature designed to reduce glare from cars behind you.
Depending on the type of car you drive and the specific components of your rearview mirror, it’s likely that your mirror has a built-in night mode with a light sensor. This technology, often referred to as an auto-dimming or electrochromic mirror, is designed to react to various light sources.
Why does my rearview mirror turn blue?
When bright lights—such as headlights from a vehicle behind you or even intense sunlight—hit the front photosensor on your rearview mirror, it triggers the auto-dimming feature. The mirror then automatically adjusts its reflectivity to reduce glare.
This adjustment not only dims the mirror but also gives it a distinct bluish tint. This helps minimize the amount of light that gets reflected directly into your eyes, thereby reducing glare and improving nighttime driving safety.
The science behind blue-tinting mirrors
Auto-dimming mirrors use an electrochromic mirror that changes color when power is applied to it. There are generally two sensors on this type of mirror, one facing the front and another facing the back. The frontal sensor gets a reading of the ambient light and if it determines that you are driving in a dark environment (at night, in a tunnel, etc.), it will compare the light from the other sensor facing your rear windshield. If it notices that the rear is much brighter than the front, perhaps if a car following you has their high beams on, it will trigger the electrochromic mirror to darken.
The blue hue is a result of the specific materials and coatings used in the mirror’s construction and this pale blue becomes increasingly obvious as your mirror darkens.
Noticing the blue tint in bright sunlight?
As stated, in normal operation the blue tint shouldn’t be too obvious because dimming should not be activated. However, if you’re finding that your mirrors are dark blue even when it shouldn’t be, then you might have a problem with the sensors or some electrical fault that is activating the electrochromic mirror.
There are a few key components that will cause this. Firstly, light might not be getting to one of your sensors or both of your sensors which is causing them to be a bad reading of the lighting situation. Secondly, your microprocessor in the mirror might have a problem, hence triggering the dimming despite there not being a situation that warrants it.
Xuyun Zeng is a content strategist with a wide-ranging content background including tech, journalism, cars and health care. After graduating with highest honors in journalism, Xuyun led a newspaper to win eight awards, helped start an award-winning film industry podcast and has written over a hundred articles about cars repair, state laws and insurance. Prior to joining Jerry, Xuyun worked as a freelance SEO consultant with a mission to create the best content that will help readers and grow organic traffic.
Expert insurance writer and editor Amy Bobinger specializes in car repair, car maintenance, and car insurance. Amy is passionate about creating content that helps consumers navigate challenges related to car ownership and achieve financial success in areas relating to cars. Amy has over 10 years of writing and editing experience. After several years as a freelance writer, Amy spent four years as an editing fellow at WikiHow, where she co-authored over 600 articles on topics including car maintenance and home ownership. Since joining Jerry’s editorial team in 2022, Amy has edited over 2,500 articles on car insurance, state driving laws, and car repair and maintenance.
