10 Car Repairs You Should Never Try to Do Yourself

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A Japanese tuning shop outside of Nagoya works on a series of vehicles that need servicing | Micah Wright/Autos Cheat
A Japanese tuning shop outside of Nagoya works on vehicles that need servicing. | Micah Wright/The Cheat Sheet

There’s nothing more frustrating than getting excited about fixing a problematic automobile all by yourself only to discover that the repairs required are well beyond your skills as a mechanic. Yes, there are easy fixes anyone can do in their garage, but knowing when to turn things over to the professionals is perhaps the most invaluable piece of advice we can offer.

As with all things in life that break, there is a time when you must decide whether it is wiser to cough up the cash and have someone else tackle the repair or attempt to save some greenbacks and try fixing it on your own. There really is no right or wrong answer here. It just depends on the task at hand and how confident you are that the problem can get fixed properly.

Nevertheless, there are times when the average DIYer shouldn’t even begin to ponder particular automotive repairs. Here are 10 prime examples of when it’s best to back off in order to protect your vehicle and yourself.

1. Body work and paint

Bondo body filler
Working with toxic products, such as body filler, requires lots of practice, tools, and a work area with ample amounts of lighting and ventilation. | Micah Wright/The Cheat Sheet

Repairing damaged body panels and applying paint is an expensive, messy, noxious, and time-consuming process. Between all the fumes and required training, it’s one of those repairs for which specialized professionals are the obvious choice.

By tackling this fix on your own it’s easy to end up with a terrible job with bubbles, sanding gouges, and a multitude of other issues. Painting isn’t much better. Shoddy coverage, insufficient clear coats, “orange peel,” and overspray issues are a dime a dozen if performed in a makeshift paint shop. We understand this is an expensive repair — but so is realizing that it all needs to done over again.

2. ECU fixes and tuning

Cobb Tuning offers some amazing plug-and-play solutions if you want to recalibrate your car's performance capabilities, but one wrong move and you could be shopping for a fresh engine
Cobb Tuning offers some amazing plug-and-play solutions if you want to recalibrate your car’s performance capabilities, but one wrong move and you could be shopping for a fresh engine. | Cobb Tuning

A good rule of thumb is to always leave automotive computer repairs alone. Unless you are a certified ASE master technician, there’s no reason for you to be fooling with air/fuel ratios, shift points, and redline limiters. Let an experienced tuner take over and fix whatever issues or fine tuning needs might be required.

3. Windshield replacement

Cracked windshield
A cracked windshield is a notoriously tricky component to replace on an automobile, and most mechanics will send people to a glass specialist instead. | Micah Wright/The Cheat Sheet

This is one of those repairs that all drivers dread. And at around $200 to $300 a pop, it’s easy to understand why. While you can always carve a used one out of a donor car in the junkyard for next to nothing, by the time you pay for all the adhesive, fresh clips, and any required window trim pieces, that quote you got from the shop down the street doesn’t seem all that bad. Spend the dough, and get a brand-new windshield professionally installed. The last thing you need is a leaky piece of glass ruining your interior.

4. Electrical gremlins

An Ascension Motorsport Harness for an LS swapped car ready to go to a happy customer
An Ascension Motorsport Harness for an LS swapped car is ready to go to a happy customer. | Ascension Motorsport via Instagram

Outside of swapping in a fresh fuse or relay, staying away from run-of-the-mill electrical repairs is a wise move. There are endless yards of electric wiring in a car (a Bentley Bentayga utilizes an adult’s weight in wiring), with many connectors, sensors, and computers plugged into them. If certified industrial electricians tend to shy away from automotive electronic gremlins it might be best if you do the same.

5. Fuel system fixes

Injector Dynamics ID1000 high volume fuel injectors
Injector Dynamics ID1000 high volume fuel injectors | Injector Dynamics

Here’s a great way to blow up your car and get third-degree burns in the process. Fuel systems have the capacity to cause headaches, garage fires, and even unconsciousness. Our recommendation is to play it safe and leave anything having to do with replacing a fuel pump, tank, injectors, rails, or pressurized lines to the pros.

6. Snapped coil springs

Always under extreme pressure and strong enough to kill a full-grown man, the springs on a car are tightly wound mouse traps. You get one guess as to who’s at risk of getting caught. This video explains the dangers associated with swapping springs, and though it is by no means an impossible task to undertake, the risks involved make it a chore that’s best to hand off to a mechanic.

7. Transmission fixes

car parts
Rebuilding a transmission and then swapping it into a car is never an easy task and should only be attempted by a trained professional. | driving 4 answers via YouTube

Have you ever looked inside the bell housing of a car’s transmission? It’s a twisted maze of gears, tensioners, bearings, and rods, all of which have to fit right back where they belong in order to work. Think swapping a transmission is the way to go instead of rebuilding one? Good luck getting all those sensors out of the way without breaking a few crusty clips and smashing a finger or two. Even automatic gearboxes on a small four-cylinder weigh a lot, so you’ll also need some serious assistance in order to get a new gearbox to go in its home.

8. AC system restoration

The rear climate controls on the Range Rover Td6
The rear climate controls on the Range Rover Td6 are a snazzy and expensive component to fix. | Micah Wright/The Cheat Sheet

The amount of parts requiring replacement on a modern vehicle when an AC compressor locks up is staggering. Once that crucial component seizes up, it will more than likely send tiny shards of metal through every inch of the system, meaning every line and fitting needs to be replaced along with the condenser, evaporator, compressor, and various other items. Expensive, time consuming, and dangerous, this is a task that even trained professionals dread doing.

9. Brake plumbing and reservoir replacement

Replacing a busted brake reservoir means some very specific safety steps must be initiated before getting back on the road. | Micah Wright/The Cheat Sheet

Even the small stuff, such as replacing your brake pads and rotors, can put you in dangerous territory really quickly. Being able to stop safer than when you started is the reason we bleed brakes and upgrade pads and rotors with aftermarket options. But things don’t always go according to plan. So when something, such as a master cylinder or a line, rusts in half, it’s usually best to take your car to a shop for repairs in order for everything to be flared and fixed properly.

10. Defective airbag fixes

This last warning should be a bit obvious, but that doesn’t stop people from trying to swap out detonated or defective airbags on their own. Unplugging everything properly and removing the old unit is one thing. Fitting in the fresh airbag can be a completely different story. Although these kinds of repairs might save you money (when not covered under warranty or recall), relying on trained professionals will provide you both with peace of mind and factory fitment without all the headaches.