This is often the culprit when your engine won't start. All batteries weaken over time. In addition, infrequent use, a lot of short trips, or multiple accessories being used when the headlights are on can leave the battery undercharged. If you forget to turn off a light or you listen to the radio with the engine off, the battery could be too weak to start the engine when you need it.
How to prevent it
Although the effect of a drained battery often shows up on cold mornings, it's the high temperatures of summer that usually do the most damage. So a battery can go at any time. That's why you should have the battery and alternator tested as part of an annual safety inspection. If you need to buy a new battery, see our buying advice.
Flats and blowouts can be caused by a road hazard, a tire defect, or lack of care. At best they interrupt your trip and force you to change the tire or call for assistance; at worst they can cause you to lose control of the vehicle. If you experience either, take a firm grip on the wheel and gently guide the car off the road as soon as possible.
How to prevent it
Many tire problems result from underinflated tires that overheat. Keep all tires, even the spare, properly inflated to the automaker's recommended pressure by checking them at least monthly. And pay attention to warnings from the car's tirepressure monitoring system, if there is one. Also inspect the tire sidewalls for bulges or cracks. If you see such warning signs, replace the tire immediately. Replacing all four tires at a time is best, and it's a must on all-wheel drive vehicles. See our tires Ratings and buying advice for which to buy.
An undetected leak in a critical system can be devastating, possibly resulting in a blown engine or transmission or even brake failure.
How to prevent it
Check the car's fluid levels regularly; refer to your owner's manual. Also look for leaks on the pavement where you park. Black drips are oil; green, orange, or yellow are coolant; and brown or reddish oily drips can be transmission or brake fluid. Any of those can spell trouble. Have a mechanic inspect the car if you spot any fresh leaks.
Many accidents are a result of poor visibility. Often you don't realize your wipers are shot or the washer tank is empty until your visibility is limited, such as in a heavy rain or snowstorm or in the glaring sun with a dirty windshield. And a torn wiper blade can allow the wiper arm to rub against the glass, possibly ruining the windshield.
How to prevent it
In our tests, we've found that wipers usually degrade in performance after only six months. Get new ones at least twice a year; the Valeo 600 Series, RainX Latitude, Anco 31 Series, and Michelin RainForce top our Ratings. Keep the windshield-washer reservoir full. Pack spare wiper blades and a gallon of nonfreezing washer fluid in the trunk.
When a fuse goes, it can disable a critical electrical system, such as the headlights, defroster, or antilock brake system, any of which could lead to an accident.
What to do
You can't prevent an electrical problem, but a blown fuse should be the first thing you check if your car experiences one. Carry a selection of spare fuses and a fuse puller in the car; fuse kits (about $5 to $20) are available at auto parts stores. Check your owner's manual for the correct type and amp ratings, and for how to replace them. Never replace a fuse with one of a higher amp rating. If the same fuse blows repeatedly, have a mechanic inspect the system.
It can disable the car's water pump or alternator, leading to battery failure or engine overheating. And when it comes to maintenance, belts are easy to forget.
How to prevent it
Periodically check the belts under the hood visually and by feeling them. If any one has cracks or the rubber is fraying or feels brittle, it should be replaced. If there's a lot of slack in the belt, the underside is shiny, or you hear squealing while driving, it should be adjusted or repaired. Most drive belts should be replaced after about 60,000 miles; see your owner's manual.
We've all done this. At best, it's a minor annoyance; at worst, it's a serious problem when you're in an unsafe environment.
How to prevent it
Keep a spare door key handy. Some carmakers provide a valet key or a plastic key for emergency use. If it won't fit in a purse or wallet, consider putting it in a magnetic box ($5 to $10) and hiding it beneath the car or behind the license plate. Often a dealer can cut a door key for much less than what a locksmith would charge if you provide the car's vehicle identification number and registration. Telematics services, such as GM's OnStar, can unlock a car remotely. For more advice, see our report on what to do if you lock your keys in the car.
For more information on car repairs and maintenance, see our guide.
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