A lot of DIYers have—or develop over time—a holier-than-thou attitude towards owners’ manuals. Tossing them aside becomes an odd bragging right. But your owner’s manual has some choice bits of information that could save you from headaches down the road—and maybe even save your life.

Don’t get me wrong: There is a lot of useless crap written in manuals. I’d wager that 10% of what’s inside is valuable information. No one wants to sit down and read it, but here’s the good news: If you know what to look for, you can get all the useful information by skimming, without dealing with any of the junk. Here’s what you actually need to read.

Safety Information Keeps Your Fingers and Eyeballs Intact

Depending on how you look at it, the safety warnings plastered in manuals can either be intimidating or annoying. If you’re leaning towards the former, just know that it’s mostly legal fluff the manufacturers put in to cover their butts. The section warning you not to juggle your circular saw exists because an idiot probably did that once and successfully sued the manufacturer.

user manual being used for repair

There’s some really useful information in the safety section, though, like how to properly operate the device, especially if it’s something that could cause injury. The owner’s manual for a DeWalt table saw, for instance, shows proper hand placement while operating the saw in different modes (pages 11-13), so you don’t accidentally cut a finger off, as well as what not to do while the blade is spinning (like trying to retrieve things near the blade). These guidelines may seem obvious to some, but one trip down YouTube lane will prove how many people jump into projects using unsafe practices.

Here’s something less obvious: The owner’s manual of a lawnmower or weed trimmer will tell you to always disconnect the spark plug whenever performing maintenance, so there’s no chance you might start up the engine accidentally. I didn’t know this (or really even thought about it) until I read the owner’s manual.

Noting Key Specs Helps with Repair and Maintenance

Even the best fixers won’t remember every little thing about their devices. Thankfully, owners’ manuals contain specifications that can aid in a repair or maintenance task. Put them in a notebook or a notes file for easy access, or bookmark that particular section in the manual if you refer to it often.

information in repair user manual

Vehicle owners’ manuals will list the type of oil it takes and how much of it, tire pressure information, the weight of the car (so you know if your jack can lift it), towing capacity, and fuse box diagrams, just to name a few things.

Various household electronics (think stereos, microwaves, etc.) often list specs like voltages and amperage in the manual, too. So if it’s not working correctly, you can take a multimeter to it, see the amp draw, and compare it to what it should be drawing using the info in the manual. Knowing that information can help you quickly figure out what might be wrong with a device (and thus, what needs fixing).

Maintenance Schedules Keep Your Stuff Lasting As Long As Possible

Even the hardiest devices need a little spring cleaning now and then, and your owner’s manual will tell you exactly what maintenance tasks to put on your calendar.

maintenance user manual

For instance, did you know that you need to drain your water heater about once a year to flush out all the sediment buildup? You also need to replace the anode rod every few years, which collects corrosive elements in the water to prevent rusting. You probably wouldn’t have known to do this if you didn’t read the owner’s manual, but I guarantee you’ll hear about it when the plumber comes over to replace your rusted-out water heater.

And in every vehicle’s owner’s manual, you’ll find a maintenance schedule detailing how often all the fluids need to be changed, as well as consumable parts like brake pads, air filters, and wiper blades.

Troubleshooting Steps Are a First Stop for Fixes

If you’re already a knowledgeable fixer, you don’t need to rely on the troubleshooting section inside an owner’s manual. But for everyone else, this can be a great section to reference if your device is acting up and you aren’t sure how to fix it.

Manuals usually suggest very basic troubleshooting steps for a handful of common problems—anything even remotely complex will require more help than what the manual provides. Still, it’s a good place to reference to rule out all of the simple fixes.

Part Diagrams Answer “What Is This Thing and What Does It Do?”

Whether it’s an appliance, lawn mower, car, or power tool, the owner’s manual will usually have an illustration of the product, along with arrows naming the specific parts that are worth knowing. That way, if you ever need to replace a component (or just have a question about it), you can refer to it by its actual name at the hardware store, rather than telling the nice employee that you need a replacement for “this thingy.” It’s also quite handy when you need to Google for replacement parts or fixing tips.

repair diagram in user manual

Part diagrams are also helpful for finding specific parts on a device if you know the name of the part, but don’t know where it’s located. For example, if you’re troubleshooting your water heater and asking questions on a plumbing forum, you might get a reply that just says, “look for buildup on the pressure relief valve.” If you don’t know where that valve is located on the water heater, a quick glance in the manual will show you.

Replacement Part Information Make Repairs a Breeze

Too many manufacturers don’t sell replacement parts for the products they sell, nor tell you the part numbers or where else you might buy parts. Some manufacturers are happy to provide replacement parts, however, and that info can usually be found in the owner’s manual.

replacement parts in a user manual

My lawnmower’s manual lists a handful of replacement parts available, along with their respective part numbers. From there, I can go to the hardware store or search for the part number on Google and get it shipped to me. If your manual includes replacement part details, take a photo with your phone, write it down, or hold onto that manual with dedication.

It’s easy to just toss aside the owner’s manual of any given product the minute you get the box open. It can practically become muscle memory. But amidst the fluff, you can find some useful information in there worth saving.

Craig is a staff writer at iFixit, as well as a general tech nerd, maker, fixer, DIYer, motorcyclist, party game enthusiast, baseball fan, crazy cat dad, and proud introvert.

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