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What is Blind-Spot Monitoring and How Does it Work?

Blind-spot monitoring is a convenient feature found in many new cars. While there’s still no replacement for turning your head to check your blind spot, this type of monitoring system can help keep an eye on those spots that are hard to see with your mirrors.

This technology is statistically proven to reduce injuries caused by lane-change crashes, making it worth serious consideration when shopping for your next car.

Let’s take a closer look at what blind-spot monitoring is, how it works, and whether your next car should have it.

What is Blind-Spot Monitoring?

Blind-spot monitoring is a pretty self-explanatory feature. It monitors your blind spots and alerts you if you’re trying to make an unsafe lane change that could result in a collision with another vehicle. This is often done with visual and audible alerts with lights and beeps to help prevent an accident.

On most cars with blind-spot monitoring, it stays on in the background and doesn’t require any intervention from the driver. In some cases, you can turn it off if you’d like or modify the alert system, but it’s best to leave it on in normal driving conditions.

How Does Blind-Spot Monitoring Work?

Audi Blind Spot

Blind-spot monitoring uses sensors on the outside of the car to keep an eye on your blind spot. If these sensors detect a car in your blind spot where it might not be visible in your mirrors, a little light will turn on to let you know. These lights are usually on the inside of the front doors near the mirrors or on the mirrors themselves.

If you turn on your turn signal while there’s a car in your blind spot, this feature will give you an audible alert. The car will beep to let you know that it’s not a good time to change lanes because of the risk of an accident. It might be annoying, but it could save you from a dangerous and costly accident.

Does Blind-Spot Monitoring Work?

The short answer is “yes.” Blind-spot monitoring has been proven to reduce lane-change crashes, preventing injuries and costly damage. A study by the IIHS found a significant 23% drop in lane-change crashes with injuries in cars with blind-spot monitoring.

Benefits of Blind-Spot Monitoring

  • Safer lane changes — The biggest benefit of blind-spot monitoring is safer lane changes. Studies have shown that cars with blind-spot monitoring result in fewer lane-change accidents.
  • Prevents injuries — Fewer lane-change accidents mean fewer injuries.
  • Prevents damage — A prevented accident means a prevented trip to the shop for costly repairs to the body and mechanical components of your car.
  • Turn your head less — When making a lane change, you should still check your blind spot by turning your head and looking. However, if you need to change lanes and this feature tells you there’s a car in your blind spot with a little light, it will save you a head turn, and you can wait until the light is off to check.

Additional Safety Features Based on Blind-Spot Monitoring Systems

How blind-spot monitoring works on some vehicles.

Radar-based blind-spot monitoring (BSM) systems provide the foundation for rear cross-traffic alert (RCTA). This feature works when you’re reversing from your driveway or a parking space and you can’t see if traffic is approaching from the sides.

Typically, RCTA provides an audible alert and a visual warning on your car’s reversing camera, which is where you’re most likely looking while you’re backing up. Note that radar-based BSM systems usually, but not always, include RCTA. Sometimes, RCTA is an extra add-on.

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Lane-change assist (LCA) is another feature that radar-based BSM systems support. This technology warns you when another vehicle is rapidly approaching from behind so that you don’t change lanes into its path. This is an emerging technology and is not included with all BSM systems.


Increasingly, automakers are offering active versions of BSM. This means that if you ignore system warnings, the vehicle will actively attempt to prevent you from changing lanes. Through the brakes and steering, an active BSM system will try to keep your car in its lane until the threat of a collision has passed. Active BSM is typically an optional upgrade.

Where to Find a Blind-Spot Monitor

Blind-spot monitoring is getting increasingly common in new cars. Affordable cars and SUVs like the Toyota RAV4, Honda Civic, Chevrolet Equinox, and many more have blind-spot monitoring available as an option.

A handful of affordable new cars offer blind-spot monitoring as standard equipment. A few include the Hyundai Elantra, Kia Forte, and Nissan Sentra, all of which have starting prices around $20,000.

Aftermarket Blind-Spot Monitors

It’s possible to add blind-spot monitoring to your car with an aftermarket option. While vehicles with blind-spot monitoring built-in are getting more affordable as time goes on, an aftermarket solution is more value-conscious than buying a new car just to get this feature.

An aftermarket blind-spot monitoring system typically consists of two sensors and two indicators (one of each for each side of the car). The sensors keep an eye on your blind spots and tell the indicators to turn on when they need to.

You can find these at online retailers like Amazon, starting at around $100. If you’re not comfortable installing it yourself, we recommend professional installation at a local mechanic.

Should You Rely on a Blind-Spot Monitor?

Blind-spot monitoring creates an extra layer of safety and convenience, but it’s still no replacement for alert driving. You still need to check your blind spot the old-fashioned way while changing lanes. However, this feature can conveniently tell you if someone is in your blind spot, indicating that it’s not a good time to change lanes. You can plan your lane change accordingly if you see that little light turn on.

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Can blind-spot monitoring be added to your car?

Yes, there are aftermarket options for blind spot monitoring. Adding it to the car you drive now is a more budget-friendly alternative to buying a car with the feature built-in.

Is blind-spot monitoring standard in new cars?

Some new cars like the Nissan Sentra and Kia Forte have standard blind-spot monitoring. For most new cars, it’s optional.

Do SUVs have blind-spot monitoring?

Blind-spot monitoring is a common option on a wide range of SUVs.

Our editors are here to make car buying easier. We’ve driven, reviewed and compared thousands of cars. We’ve bought and sold more than our fair share, too. And as part of the sprawling Cox Automotive group of companies, we have exclusive access to a range of valuable data and insights. Whether you’re looking for the best car, the best deal or the best buying advice, you can trust... Read More about Autotrader

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