The Top 15 Most Frequently Replaced Auto Parts

Even though major car brands all have their differences, most cars are designed and built using the same fundamental working principles. This also means that most vehicles tend to have the same problems as they age.

Yes, different powertrain configurations, special safety features, and brand-specific equipment may bring different car troubles but, when it comes down to the main elements and most basic systems, cars often need to go to the repair shop for the same reasons. No matter if the components break because they are under more stress than others or the design is originally flawed, some auto parts simply need to be replaced more often than others.

To give you a better idea of the components you’ll probably need to replace in the future or which one to suspect first when a car problem occurs, here’s a list of the top 15 most frequently replaced automotive parts.

Regular maintenance parts

1. Oil filter

No matter what type or model of vehicle you own, the part you’ll need to replace the most is the oil filter. The lubrication system is vital to the proper operation of any internal combustion engine. Depending on the car manufacturer, how your vehicle’s lubrication system is designed, and the type of oil used, you’ll need to get the engine oil and oil filter replaced every 5,000 km to 20,000 km.

2. Air filter

The engine air filter will also need to be replaced on a regular basis. Most car manufacturers will recommend the replacement around 40,000 km but you really need to replace it only when it’s dirty or clogged. Driving regularly on unpaved or gravel roads will greatly shorten the lifespan of your air filter.

Failing to replace a dirty air filter will minimize the airflow to the engine and will reduce your vehicle’s fuel-efficiency. Air filters are usually pretty inexpensive so don’t hesitate to replace it when needed.

If you frequently drive off-road or live in a dusty or arid climate, installing a “wet” air filter might be a good idea to save money on air filter replacement. This type of filter can be cleaned and reused indefinitely. Be warned that “wet” filters, unlike dry filters, need to be properly oiled to do their job. A wet filter not cleaned, oiled and maintained often enough will cause more harm than good to your engine in the end.

3. Drive belt

Since the alternator, water pump, oil pump, power-steering (unless your car is equipped with an electric power-steering system), and A/C compressor are all powered by the drive belt, your vehicle won’t go that far without a drive belt in good working condition.

Even though drive belts are manufactured using a rubber-type specifically made to withstand the biggest temperature gaps possible, the rubber will end up drying out and will start to crack with time.

When the cracks are big enough, the belt will loosen up and could slip on the pulleys, producing a squealing sound. When it happens, failing to replace it in time could lead to the belt tearing up and ultimately bringing the car to a halt. Without a drive belt, the alternator cannot do its job anymore and the car will stop as soon as the battery is drained from its power.

Belts should be inspected at every oil change and replaced as soon as surface glazing or cracks are detected.

4. Cabin filter

Cabin filters, also called pollen filters, are used to clean the air entering the cabin from contaminants like pollen and dust. A clogged cabin filter will greatly reduce the efficiency of your climate control system. There’s no fixed service interval for this part since it depends on the climate you live in, the kind of roads you travel onto and the mileage you drive every year.

Most cabin filters are located behind the glove box and are easy to replace. Simply unhook the glove box, remove the cabin filter cover and pull out the filter. Replacing a cabin filter takes a maximum of 10 min and most car dealers will often charge over $60 to do it.

Braking system

5. Brake pads and rotors

Right after oil changes and routine maintenance work, brake pads and rotors replacement are the most common job mechanics must perform daily. Brakes are used every time you drive your car, so they’ll need to be replaced from time to time.

When you step on the brake pedal, the brake pads are pressed onto the rotors and slow down the car. The rubbing of both components on each other will lead them to wear out and need to be replaced.

Furthermore, in the case of an emergency brake situation, the rotors’ temperature will suddenly rise and could cause the rotors to warp. Warped disc brakes will make the brake pedal vibrate and will cause premature wear of the brake pads.

To ensure your brakes last as often as possible, make sure to have your brake system serviced every year or 24,000km, depending on whichever comes first.

6. Wheel speed sensors

Wheel Speed Sensor

Whenever an ABS warning light is popping up in the dashboard, the problem is usually related to wheel speed sensors. These sensors are located on the knuckles, pointing towards the speed sensor rings installed on the driveshafts or the wheel bearings.

Because of their location, they are constantly exposed to the outside elements while you drive your car. They get filled with snow and salt in the winter and water and dirt in the summer. Consequently, it’s common to see rust infiltrating the sensors and damaging the inside components, leading to false readings and DTCs being recorded in the PCM.

Using an OBD2 scan tool to read the DTC codes will let you know which sensor is damaged and isn’t sending data to the powertrain module anymore. When in doubt, test the voltage output in the suspected wheel speed sensor’s connector. Refer to your vehicle’s repair manual for the correct specification and replace the wheel speed sensors if the value is out of the normal threshold.

Suspension system

7. Stabilizer links

Stabilizer link

Suspension components are constantly under stress. They have to absorb the shocks coming from all bumps and potholes on the roads. Therefore, it’s only natural that these auto parts need to be replaced more often than others. Stabilizer links are, by far, the most commonly replaced of all the suspension components.

This may or may not be true depending on the car model you drive. Car manufacturers use different link designs, and some are simply more efficient and reliable than others. For example, Dodge Chargers will rarely have stabilizer links problems because they are bigger and sturdier than most. Hyundai and most Korean vehicles, on the other hand, often need to replace a link or two every 30,000km or so.

Conversely, stabilizer links on Korean cars are often quite inexpensive and can usually be replaced in under 1 hour while other suspension problems on American cars may take longer to repair and be more expensive in the end.

8. Ball joints

Ball joints are used to allow your front wheels to move on the vertical axis. Every time your car hits a crack or a small bump on the road, the ball joints are solicited.

Ball joints are lubricated from the factory and a rubber seal is used to prevent water and dirt to enter. After a while, the seal will dry out, crack and rust will start to accumulate on the bottom of the ball joint, pushing the grease out.

Water will also be able to enter and will wash out the remaining grease, Whenever it happens, the ball joint will become loose in the socket and a knocking sound will be heard every time that wheel hits a bump and a squealing sound could be heard when the steering wheel is turned.

A loose ball joint can be tested with the wheel raised on a jack, by shaking the wheel up and down. If the wheel has play in it, the ball joint is faulty, and it will need to be replaced.

Be aware that failing to replace a loose ball joint could lead to more expensive repairs and even a car crash.

9. Control arm bushings

These bushings are located at the other end of the control arms holding the ball joints. They typically don’t include rotating joints like ball joints do and instead use polyurethane bushings to allow the arms to go up and down. As with any other rubber components, they tend to dry out and crack with time.

In most cases, when a control arm bushing is faulty, you should be able to notice the inside sleeve part sliding out of the bushing. When it happens, a low “thump” or metal noise will be heard when driving over potholes.

Depending on the car model, control arms bushing may be expensive to replace. For example, Mazda 3s are equipped with bolt-on front bushing that can be replaced in about an hour while replacing rear bushings on Ford Explorers require the complete disassembly of the rear drivetrain and about 6-7 hours of work.

Car manufacturers have designed better and more reliable bushings in recent years. Faulty control arm bushing may not be as frequent as they used to be on more recent vehicles. However, if you own a car made before 2015, be prepared to replace these bushings once the car is at least 8 years old.

10. Shock Absorbers

Shocks absorbers, also called suspension struts, are a little bit different. Unlike other suspension components mentioned before, they rarely need to be replaced because of water causing rust and creating a play inside of it. Instead, struts usually need to be replaced because they are leaking.

The oil contained inside shock absorbers is used to absorb the unevenness of the road. When the seals dry out, the oil will start to leak around the shock’s rod and the oil level will gradually lower until the strut has no dampening effect anymore. Once the fluid level inside the shock reaches a certain level, you should easily notice how the car starts to bounce an excessive amount of time after each bump on the road.

To test it, shake the car while it’s parked on a level surface and count the number of bounce after you let it go. A normal suspension should stop the car from moving in 1½ bounce. Visually inspecting the shock can also help. If the shock is greasy, the oil is leaking somewhere, and it should be replaced right away.

Steering system

11. Inner tie rods and tie rod ends

Tie rods and tie rod ends do the same job as ball joints do, if only that they allow the wheel to move horizontally instead of vertically. They are built following the same basic principle and thus are subject to the same defects. Rust will usually be able to enter between the ball and its housing and will cause a play in the wheel.

The inspection process is also the same as with a ball joint. Raise the car and inspect for play while shaking the wheel from side to side. Be warned that a loose inner tie rod will feel the same as a loose tie rod end. To isolate the problem, touch both components alternately while shaking the wheel.

If you have access to a car hoist, alternately pulling onto each component while shaking the wheel could help too. If the play disappears when you are pulling onto the tie rod end, the problem comes from that component. If not, the problem comes from the inner tie rod instead and it will need to be replaced.

Ignition system

12. Spark plugs

On all internal combustion engines, it’s the spark plugs’ job to ignite the air/fuel mixture to create an explosion and ultimately make the car move forward. Spark plugs must withstand an enormous amount of pressure every time an explosion happens. On a typical engine turning at 2000rpm, each spark plug will fire 1000 times per minute and each explosion can produce pressure reaching over 30,000 lb/ft2. The temperature inside the cylinder can also reach over 4,500 °F right after the explosion.

As time passes, the center electrode will wear out and misfires could occur. Excessive heat can also cause the insulator to crack and the faulty spark plugs will end up being short-to-ground and won’t spark anymore. When it occurs, there’s nothing else to do than to replace the plugs altogether.

Different types of spark plugs will need to be replaced at different intervals. For example, cheap copper plugs usually last around 50,000km while iridium plugs often last more than 120,000km. Iridium plugs can cost 5 to 10 times more than standard ones.

Choosing the right ones for your vehicle depends on how complicated replacing the spark plugs is. If putting new plugs in requires the disassembly of the intake manifold like on a V6 engine, for instance, installing iridium spar plugs might be a good idea.

Engine Management system

13. O2 sensors

O2 sensors are used to adjust the air/fuel mixture entering the engine. They are installed at different locations on the exhaust system and monitor the amount of unburnt fuel in the exhaust fumes in real-time. Once again, components subject to higher temperatures and excessive pressure tend to fail the most often.

On most vehicles, an O2 sensor is installed right on the exhaust manifold and another one right after the second catalytic converter. Of course, these are the hottest parts of the exhaust system.

Such a high temperature over a long period will inevitably damage the internal components of the O2 sensors and they will need to be replaced. Failing to do so will lead to an incorrect air/fuel ratio greatly reducing the fuel efficiency of your vehicle. Driving with a bad O2 sensor could also cause collateral damage to other expensive components such as the catalytic converter and the emission control system.

Charging system

14. Battery

Another frequently replaced automotive part depending on where you live is the battery. Cold is the number one enemy of car batteries simply because the chemical reaction inside of them proceeds more slowly in cold weather. Sub-zero temperatures will even slowly drain the power contained inside the battery and will also put a strain on the inside components like the cathode plates.

After a while, as the plates degrade, the battery won’t be able to hold enough power to allow the car to start. Such a situation will be exacerbated during the winter season as starting the car also requires more power than usual.

On the other hand, warm weather is also detrimental to a car battery as it promotes sulfation and water loss. If you live in an arid or tropical climate, buying a car battery with maintenance caps may help you extend its lifespan as it can be refilled with electrolyte as it evaporates.

A typical battery will last 4 to 5 years when used in optimal weather conditions but will quickly weaken after 3 years. Most car owners living above the 45th parallel and below the tropic of Cancer should replace their batteries every 3 years or at the first sign of weakness.

15. Alternator

As another main component of the charging system, the alternator also suffers from big temperatures changes and is co-dependant of your car battery’s health. As your battery ages, the alternator will produce more power to make up for the battery’s lack of efficiency and that often leads to premature malfunctions.

During the winter season, the alternator is also more solicited as your car requires more power to operate the climate control system, the rear defrost, the heated seats and other additional winter-related accessories.

The alternator is driven by the belt and turns roughly 4 to 5 times faster than the engine. This means that when the engine turns 3,000rpm, the alternator pulley is turning at around 12,000-15,000rpm. It’s not hard to understand then why the flimsy alternator bearing may wear out and start producing noise at some point.

It’s important to mention that, just as the battery’s health has an impact on the alternator’s lifespan, the reverse is also true. A faulty alternator will drain the battery and will affect its expected lifespan. To ensure both components last as long as possible, make sure to test your alternator at least once a year, preferably right before the winter season.

Last words

No matter if your car is American or a JDM, big or small, powerful or fuel-efficient, it will break and will need to be repaired at some point. Cars have to withstand a tremendous amount of stressful situations, pull heavy loads, drive on different types of terrain and go the distance on your next road trip across the country.

We simply can’t expect them to last forever. Make sure to have your car checked regularly and inspect the most often replaced auto parts for aging signs and damages. Taking care of your beloved vehicle occasionally will ensure it stays in perfect shape for as long as possible.

About Jean-Claude Landry

Jean-Claude is the editor of TheMechanicDoctor.com and has been a certified auto mechanic for the last 15 years, working for various car dealers and specialized repair shops. He turned towards blogging about cars and EVs in the hope of helping and inspiring the next generation of automotive technicians. He also loves cats, Johnny Cash and Subarus.

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