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  • Consult repair manuals and databases to save time and money and avoid getting injured during DIY repair jobs.
  • The recommended repair resources for DIYers are ALLDATA DIY, Mitchell 1 DIY, Chilton DIY, and Chilton/Haynes printed manuals.
  • Treat online resources as supplements to a repair manual or repair database.
  • You can also use the repair manual to educate yourself and learn about repairs your mechanic might recommend.

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.


  • Cost: $29.95/year; $49.95/5 years (discounts are available for multiple subscriptions)
  • What you get: Many professional repair shops use ALLDATA as their go-to repair database. Now, DIYers can get a single-vehicle subscription that provides access to factory repair information. That includes (but is not limited to) technical service bulletins (TSBs), wiring diagrams, and step-by-step repair instructions.

Mitchell 1 DIY

  • Cost: $19.95/month; $29.95/year; $44.95/4 years
  • What you get: Many professionals across the country also use the Mitchell 1 repair database every day. DIYers can get a single-vehicle subscription that provides access to factory repair information. That includes (but is not limited to) technical service bulletins (TSBs), wiring diagrams, and step-by-step repair instructions.

Chilton DIY

  • Cost: $24.95/month; $29.95/year
  • What you get: Chilton has been making print repair manuals for decades. Now, the brand offers detailed online repair information. You also get access to a hotline where you can ask certified technicians questions (for an additional fee).

    But unlike the repair databases listed above, the majority of Chilton’s repair information is not directly reprinted from the vehicle manufacturer. Because of this, you don’t get access to TSBs or recalls.

Chilton/Haynes Printed Manuals

  • Cost: Most manuals are $25.50 via the Chilton/Haynes website
  • What you get: If print repair manuals are more your style, you can peruse the selection of titles offered through Chilton and Haynes. You can also get many of these manuals through other outlets, such as Amazon.

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.

About The Author
Written By Automotive Subject Matter Expert at

Mia Bevacqua has over 14 years of experience in the auto industry and holds a bachelor’s degree in Advanced Automotive Systems. Certifications include ASE Master Automobile Technician, Master Medium/Heavy Truck Technician, L1, L2, L3, and L4 Advanced Level Specialist. Mia loves fixer-upper oddballs, like her 1987 Cavalier Z-24 and 1998 Astro Van AWD.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : Maintenance , DIY , For the Car Owner
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Where can I sign up for the DIY Manual

John F

Another excellent article by Mia Bevacqua. Yes, Knowledge is Power. And having the correct information is priceless, whether doing your own repairs or having a mechanic make the repairs.

I’ve only bought two new cars from the dealership in my lifetime. Each time I bought the manufacturer’s Shop Service & Repair Manual and Electrical Wiring Diagram Manual. The entire manuals were dedicated to my specific Make, Model & Year. The information is even much more detailed than any of the excellent third-party repair manuals.

I owned 4 other cars that I bought used, less than 5 years old, and I was able to buy the same OEM Shop manuals, used, online. Most OEM manuals are still available on Ebay going back 30+ years.

They contain a wealth of information. Many times, I had planned to do a repair myself, until read what all was involved. Then decided to let a mechanic do it. And other times, I thought a mechanic would have to do the repair, but learned it was less involved than I originally thought. And both cases were a win. Either I saved money on my own repairs. Or, I am confident that the repair was done correctly by a professional with the rights tools/machines.

And I learned that my car really didn’t have such a thing as a Framastat or Turbo Encabulator. 😉

Ahmed kilani

I want to thank the owner of this wonderful work that we enjoy as auto electrical technicians in solving malfunctions, regardless of the difficulties and challenges, to solve problems in the car.

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