How to Fix Your Vehicle's Blind Spot Monitoring System

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Keep your blind spot covered with this straightforward guide

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What is the side detection system?

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How do side detection systems work?

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Resetting the Detection System

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Symptoms of a Faulty Side Detection System

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Causes of Side Detection System Problems

Modern vehicles are equipped with side detection systems, which automatically warn you when another vehicle, a cyclist, or a pedestrian enters your blind spots. In some vehicles, the side detection system will automatically steer or brake for you to avoid collisions! Luckily, it’s usually very easy to get a buggy side detection system back online. In this article, we’ll break down what the side detection system is, how it works, and what you can do to reset the system if it’s buggy or not working.

Things You Should Know

Clean your side mirrors. The side detection system relies on sensors or cameras in or on your side mirrors, so if they’re dirty it won’t work.
Contact your dealership to see if there’s a recall, since these systems often run into weird software problems.
Use an OBD2 device to reset your vehicle’s computer if you recently made repairs or adjustments to see if the service light goes away.

Section 1 of 5:

What is the side detection system?

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The side detection system scans your blind spots for you. When a cyclist passes your vehicle or someone walks into your blind spot, does something happen in your car? If your mirror lights up, you hear a warning chime, or your screen displays a camera, that’s your side detection system. It’s designed to warn you when a vehicle, cyclist, or pedestrian enters your blind spot.^{[1]XTrustworthy SourceConsumer ReportsNonprofit organization dedicated to consumer advocacy and product testingGo to source}
- If nothing happens when something enters your blind spot or your chimes/warnings are going off when there’s nothing there, your side detection system isn’t working.
- In some newer vehicles, the service side detection system can also be adjusted to automatically turn away from collisions or stop your vehicle for you in emergencies.
- Not every car has one of these systems. In fact, most vehicles built before 2016-2018 don’t have one of these systems, and a lot of newer foreign vehicles don’t either.
- The majority of modern American vehicles have a service side detection system (or something similar to it under a different name—usually “blind spot awareness system” or “blind spot warning system”).

Section 2 of 5:

How do side detection systems work?

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Sensors, radar, or cameras monitor the sides of your car. Every side detection system works basically the same way—your vehicle is equipped with some sort of radar or sensor that constantly scans for objects or vehicles entering your blind spots. Older vehicles used literal cameras for this instead of sensors or radar.^{[2]XTrustworthy SourceConsumer ReportsNonprofit organization dedicated to consumer advocacy and product testingGo to source}
- When a vehicle or object is detected, you’ll get some kind of warning. It could be a chime, a light on your dashboard or mirror, or all of the above.
- If these chimes or lights aren’t popping on when a vehicle passes you, the detection system isn’t working as intended.

Section 3 of 5:

Resetting the Detection System

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Contact a dealership to ask about recalls and repairs. Side detection systems have historically been prone to software problems. If your system isn’t working correctly, contact a local dealership. Ask them if there are any recalls for the side detection system. If there aren’t, ask them what it’d take to reset or repair your system and take it in for repairs.^{[3]XResearch source}
- The side detection system is almost entirely software-based. There aren’t really any mechanical components. As a result, it’s not quite something you can replace or swap out if you’re a gearhead.
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Clean your mirrors and remove any debris. Every vehicle is different, but most of these systems are built into the side mirrors. As a result, your system may not work if your mirrors are dirty. Start by cleaning your mirrors with glass cleaner or white vinegar and water. Then, remove any leaves, dirt or mud you find packed around or on your side mirrors. This may fix any issues you’re having with the side detection system.^{[4]XResearch source}
- Do you see any small sensors or lenses under or inside of your side mirrors? If so, these are almost certainly your side detection system sensors. Clean them off the same way you clean your mirrors.
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Plug an OBD2 scanner into the dash and reset the computer. Many side detection systems are integrated with your vehicle’s computer, which means you can reset the dashboard light with an OBD2 scanner. Locate the OBD2 port under your steering wheel and insert an OBD2 scanner. Power the scanner on and look to see if there’s an error code for your side detection system. If there is an error, try resetting the code.
- If the error doesn’t come back, cleaning the mirror fixed the problem. If the error does come back, contact a local dealer and explain that you need them to fix your side detection system.

Section 4 of 5:

Symptoms of a Faulty Side Detection System

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If there’s any kind of error light on your dashboard about your side detection system or your blind spot system, it’s a sign that the system isn’t working correctly. This is one of those systems you should only notice when it’s actively warning you that someone is in your blind spot.^{[5]XResearch source}
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Mirror lights or warning chimes don’t come on If cyclists, pedestrians, or other vehicles pass nearby or enter your blind spot and nothing happens, your detection system isn’t working as intended. It should automatically alert you whenever something enters your blind spot, so the fact that it isn’t signaling anything means it’s not functioning correctly.^{[6]XResearch source}
- Check your vehicle’s computer settings on the main dash screen. It’s possible that you accidentally turned the system off if it never comes on.
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Lights, chimes, or warnings won’t turn off If the warnings come on out of nowhere when there isn’t anything entering your blind spots and/or the warnings won’t go away, the side detection system is malfunctioning. These warnings should turn off automatically once the obstruction is gone.^{[7]XResearch source}
- Don’t assume the system is busted if the warnings come on in whacky weather. Snow and heavy rain can confuse the sensors sometimes.

Section 5 of 5:

Causes of Side Detection System Problems

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The side detection system is basically just a couple motion sensors and a computer program. If a sensor isn’t working correctly or the software is buggy, your side detection system won’t work correctly. Either the program needs to be debugged or patched, or the sensor needs to be cleaned or replaced.^{[8]XResearch source}
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Damage to your mirrors The side detection system is almost always built into the side mirrors. As a result, if your mirrors get knocked off, hit, or generally damaged, it can mess with your side detection. Once the mirrors are repaired, ask the mechanic or dealership to reset the detection system and things should go back to normal.^{[9]XResearch source}
- During heavy rain or snow, water can get into the mirror. That water might cause your side detection system to not function correctly.