Fix Your Car Right the First Time: Why You Should Always Consult a Repair Manual

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There’s a common misconception that anyone can pick up a wrench, jump right in, and fix a car. While that may have been closer to the truth 40 years ago, modern vehicles are far too complex to repair on the fly.

Before trying to fix or diagnose a car, you should always consult the appropriate repair information for your particular application. Skipping this critical first step can cost you time and money—and potentially lead to personal injury.

Trust me, I’ve seen all of the above happen on countless occasions.

woman looking at online repair manual while fixing car
Always consult the appropriate repair information for your particular application before trying to fix or diagnose your car.

Why It’s Critical to Consult the Appropriate Repair Information

Today’s vehicles are extremely sophisticated, with miles of wiring and dozens of computers onboard. Furthermore, because all makes and models are different, a repair approach that works on one car might not work on another.

As such, it’s more critical than ever to consult a repair database (or repair manual) before working on your car. If you don’t do your homework beforehand, you risk wasting time and money by replacing unnecessary parts.

Avoid Wasting Time and Money

I have a friend who constantly tries to fix cars without consulting the appropriate repair information. That habit often leads to him replacing parts he really doesn’t need to replace, which, as previously stated, wastes both time and money.

For example, he recently called me to complain about a Honda that had its check engine light illuminated. The car’s primary computer—or the powertrain control module (PCM)—had stored code P0139 or “Heated Oxygen Sensor (Bank 1, Sensor 1) Slow Response” in its memory.

In an attempt to get rid of the code, my friend had replaced both oxygen sensors and the catalytic converter—yet the code persisted.

He finally threw in the towel and called me.

Over the phone, I was able to use a repair database called Identifix to pinpoint the problem within minutes. My research brought me to a technical service bulletin (TSB), which suggested that reprogramming the PCM would cure the issue. And so the car went to the dealer, the PCM was updated, and the problem was fixed.

The example mentioned above is just one of many similar stories. I can’t tell you how many times I’ve searched TSBs and traced wiring diagrams to diagnose cars over the phone.

Information is the key to solving difficult problems. And when it comes to fixing cars, if you don’t have that information (derived from a repair database or service manual), there’s a good chance you’ll end up chasing your tail.

There’s also the possibility of damaging your vehicle or hurting yourself.

Prevent Personal Injury

I’ve seen some scary stuff happen (or nearly happen) to people who didn’t consult the necessary repair information before working on their car.

For instance, when I was a mechanic, a customer brought his vehicle in after attempting to replace the struts. Because he had not looked up the repair information and, therefore, had no idea what he was doing, he removed the strut nut before compressing the coil spring. As a result, the coil spring went through the fender well and into the car’s hood, causing significant damage.

More recently, I saw someone handling high-voltage cables on a Toyota Prius. This individual had not disconnected the hybrid battery service plug, nor was he wearing any personal protective equipment. That’s a recipe for serious injury or death.

Obviously, he had not looked up the procedure in a repair database before jumping in.

Even when you know what you’re doing, working on cars can be dangerous. If you’re clueless because you haven’t read the repair information and safety recommendations, you significantly increase your chances of getting hurt.

laptop and tools for auto repair
There are many subsciption-based databases containing factory repair information.

Recommended Repair Resources for DIYers

When I first started working on cars as a teenager, factory repair information was kept in textbook-sized repair manuals (or on data discs).

But now, there are subscription-based databases that put the factory repair information right at your fingertips. Less comprehensive repair manuals, such as those from Chilton and Haynes, are available as well.

As I mentioned before, I get my repair information from a database called Identifix. The only downside is that this subscription-based platform costs nearly $150 a month—that’s definitely more than most DIYers are looking to spend.

Fortunately, these days, there’s a lot of repair information available to the everyday driver. Some of the best resources include:

Note: The costs listed below may have changed since the time this article was written.


Mitchell 1 DIY

Chilton DIY

Chilton/Haynes Printed Manuals

As you might guess, printed repair manuals do not include manufacturer information, such as TSBs and recalls. But they do offer repair instructions, wiring diagrams, component locations, and more.

What about using Google to find repair information? Unfortunately, many of the free online resources that pop up aren’t always accurate. To make things worse, much of the information is not vehicle-specific and could easily lead you down the wrong path.

Much like Google, not all of the information on YouTube is good information. Plus, many of the videos will not apply to your particular vehicle.

guy fixing his car
The more you know about your vehicle, the more confident you’ll feel when visiting a repair shop.

It’s best to consider online resources like these as a supplement to quality, application-specific information from a repair database or repair manual.

How Doing Your Homework Can Help—Even if You Don’t Work on Your Own Car

Okay, that’s great. But what if you don’t work on your own car? Having a print copy of a repair manual for your vehicle can still be beneficial. You can use the manual to educate yourself and learn about repairs your mechanic might recommend.

A lot of people worry about being taken advantage of by mechanics. The more you know about your vehicle, the more confident you’ll feel when visiting a repair shop.

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Mia Bevacqua

Chief Mechanic at CarParts.com

Mia Bevacqua is an automotive expert with over 15 years of industry experience. She holds ASE Master, L1, L2, and L3 Advanced Level Specialist certification, as well as a bachelor's degree in Advanced Automotive Systems.

Throughout her career, Mia has applied her skills toward automotive failure analysis inspections, consulting, diagnostic software development, and of course, freelance writing. Today, she writes for companies around the world, with many well-known clients showcasing her work.

Mia has a passion for math, science, and technology that motivates her to stay on top of the latest industry trends, such as electric vehicles and autonomous systems. At the same time, she has a weakness for fixer-upper oddballs, such as her 1987 Chevy Cavalier Z-24 and 1998 Chevy Astro Van AWD.

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