What a side rear view mirror does and why you need one
A side rear view mirror (also called a side mirror or door mirror) is the mirror mounted on the outside of your car door that shows you what is behind and to the side of your vehicle. It lets you see traffic, pedestrians, and obstacles in your blind spot — the area you cannot see in your windshield or rearview mirror. Most cars have two side mirrors, one on each door.
Side mirrors are required by law in most places because they are essential for safe driving. When you change lanes, back up, or turn, you rely on the side mirror to confirm the path is clear. Without it, you lose visibility that could prevent a collision.
The mirror itself is usually made of glass and sits in a housing attached to the door. Inside that housing is a motor (on power mirrors) or a manual adjustment mechanism that lets you tilt and angle the mirror from inside the car. The whole assembly can be damaged by impact, weather, or wear over time.
Key Takeaways
- Side mirrors show your blind spots and are legally required on all vehicles in most places.
- A cracked, missing, or misaligned mirror reduces your visibility and makes it unsafe to drive.
- You can adjust your mirror from inside the car using a manual lever or power controls, and proper positioning takes about one minute.
- Replacement mirrors cost between $150 and $500 per side depending on whether they are manual or power-operated and whether your car has heating or turn signals built in.
- A damaged mirror should be replaced before you drive on the highway, as it is both unsafe and illegal in most states.
How to position your side mirror correctly
Correct positioning is the first step to using your side mirror safely. Sit in the driver's seat and look at the mirror. You should see mostly road behind you, with just a sliver of your car's side visible on the right edge of the mirror. This positioning minimizes blind spots.
If your car has manual mirrors, you will see a lever on the door panel near the mirror. Push or pull it to angle the mirror up, down, left, or right until you reach the correct position. If your car has power mirrors, a small joystick or rocker switch on the door panel controls them. Press the switch in the direction you want the mirror to move.
Once positioned, do not adjust the mirror while driving. If you need to reposition it, pull over safely first. Many drivers adjust their mirrors once when they first get in the car and leave them alone for the entire trip.
Signs your side mirror needs replacement
A damaged or worn mirror should be replaced as soon as possible. The most obvious sign is a cracked or shattered mirror — even a small crack distorts the image and makes it unsafe to rely on. A mirror that is completely missing or hanging loose is obviously unusable.
Other warning signs include a mirror that will not stay in position (the adjustment mechanism is broken), a mirror that is fogged or cloudy on the inside (moisture has entered the housing), or a mirror that vibrates or rattles when you drive. Any of these problems means the mirror is not giving you a clear, stable view of the road behind you.
If your mirror has a power adjustment motor, test it by using the controls from inside the car. If the mirror does not move when you operate the controls, the motor or wiring has failed and the mirror needs replacement. A mirror that moves only partway or moves slowly may still work, but it is worth having checked by a technician.
What to expect when replacing a side mirror
Replacement mirrors come in two main types: manual mirrors (adjusted by hand using a lever) and power mirrors (adjusted using an electric motor and controls inside the car). Power mirrors are more common on newer vehicles. Some mirrors also include a heating element to defrost in winter, or a turn signal light built into the housing.
The cost of a replacement mirror depends on the type and your vehicle. A basic manual mirror for an older car might cost $150 to $250, while a power mirror with heating and a turn signal for a newer car can cost $300 to $500 or more. Luxury vehicles and some newer models may be higher. Labor to install the mirror typically adds $100 to $200 to the total bill.
Installation usually takes 30 minutes to one hour at a repair shop. The technician removes the old mirror by unbolting it from the door and disconnecting any wiring (for power mirrors), then installs the new one and tests the adjustment and any electrical features. You can drive the car when ready after installation.
Temporary fixes and when they work
If your mirror is cracked but still in place and still shows a usable image, you may be able to drive safely for a short time while you arrange a replacement. However, do not rely on this as a long-term solution. A cracked mirror can shatter completely without warning, especially if you hit a pothole or if the temperature changes suddenly.
If your mirror is hanging loose or partially detached, do not drive the car. A mirror that falls off while you are driving can strike another vehicle or cause you to lose control. Have it repaired or replaced before you use the car again.
Tape, glue, or other temporary repairs do not restore the mirror's function and are not legal in most places. Police can cite you for a missing or non-functional mirror, and insurance may not cover an accident if you were driving with a known defective mirror.
Power mirror problems and troubleshooting
Power mirrors sometimes fail to move even though the motor is working. The most common cause is a blown fuse. Your car's fuse box (usually under the dashboard or under the hood) has a fuse labeled for the mirror circuit. If that fuse is blown, replacing it may restore power to the mirrors. Consult your owner's manual to find the correct fuse and its location.
If the fuse is not blown but the mirror still will not move, the problem is likely a broken motor, a loose wire, or a faulty switch. These repairs require opening the door panel and testing the electrical connections, which is a job for a technician. Do not attempt to disassemble the mirror yourself unless you are experienced with automotive electrical work.
If one mirror works but the other does not, the problem is almost always specific to that mirror's motor or wiring, not a shared circuit. This makes it easier to diagnose — the technician knows to focus on that one mirror rather than checking the whole system.
Legal requirements and safety standards
In the United States, federal law requires all vehicles to have at least two mirrors that allow the driver to see the road behind the vehicle. Most states also have laws that specifically prohibit driving with a missing, broken, or non-functional mirror. Violation can result in a traffic citation and a fine.
Insurance companies may also refuse to cover an accident if you were driving with a known defective mirror. If you cause a collision and the other driver's insurance investigates, they may argue that you were driving unsafely and that your insurance should not pay. Replacing a damaged mirror is much cheaper than dealing with an insurance claim.
Beyond the legal requirement, a functioning side mirror is one of your most important safety tools. Blind spot collisions happen frequently, and a good side mirror is your primary defense against them. Keeping your mirrors in good condition is as important as maintaining your brakes or tires.
Frequently Asked Questions
Can I drive with a cracked side mirror?
Technically you can drive a short distance with a cracked mirror if it still shows a usable image, but it is not safe and is illegal in most states. A cracked mirror can shatter suddenly, and the crack distorts your view. Have it replaced before you drive on the highway or in heavy traffic.
How much does a side mirror replacement cost?
A replacement mirror costs $150 to $500 depending on whether it is manual or power-operated and whether it includes heating or a turn signal. Labor adds $100 to $200. Luxury vehicles and newer models may cost more. Call a repair shop with your vehicle's year, make, and model for an exact quote.
What if only the glass is cracked but the housing is fine?
Some repair shops can replace just the mirror glass rather than the entire assembly, which costs less than a full replacement. However, this is not always possible — it depends on how the mirror is constructed and whether the glass is glued or bolted in. Ask your repair shop whether a glass-only replacement is an option for your vehicle.
Do I need to replace both mirrors at the same time?
No. You only need to replace the mirror that is damaged. However, if both mirrors are old and one is failing, it may be worth replacing both at once to avoid a second repair trip soon after. Ask the technician whether the other mirror shows signs of wear.
Why does my power mirror move slowly or get stuck?
A slow or stuck power mirror usually means the motor is wearing out or the adjustment mechanism has debris in it. This is a sign the mirror will fail soon. Have it inspected by a technician, and plan to replace it within the next few months before it stops working entirely.