We've all been there: you're driving along, minding your own business, when all of a sudden your check engine light comes on or you begin to hear a mysterious rattle that you can't quite identify. At that point, you have two choices: take your car to the repair shop or take the DIY route and figure it out yourself! If you're a DIY enthusiast hoping to troubleshoot an automotive issue before it becomes a major concern, here are 10 car diagnostic tools you shouldn't be without.
10 Car Diagnostic Tools for DIYers
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Scan Tool
The top end of the technology ladder is held by a scan tool. This car diagnostic tool plugs into the OBD-II port (“OBD” is an acronym for on-board diagnostics, and the “II” designates the second generation of these ports, in use since 1996) and delivers a wide range of information gathered from your car’s computer, and can give you insight into how serious the problem might be.
“For example, one common engine fault is P0440, ‘problem with evaporative emission system’,” says Elizabeth Kerstetter of OBD Experts.. “Sounds scary but this fault can be triggered by not tightening your gas cap properly after getting gas. That’s a fault anyone can repair.”
If you decide to buy a scan tool, you may notice a wide range of prices on these tools. Much of the price is determined by the depth of the information in its database and the way it delivers that information to you. Scan tools may be wired or Bluetooth, and often connect to your Wi-Fi network in order to access an up-to-date online database of information. In fact, newer models often have they ability connect to your smart phone, literally putting the power of computerized diagnostics in the palm of your hand.
“I recommend that customers purchase a good scan tool because it will generate its initial investment cost within two scanning sessions,” says Alan Gelfand, owner of German Car Depot. “A tool purchase costs less than two diagnostic fees from a repair shop, and ownership of a decent scanner transforms customers into neighborhood car experts, since they can provide assistance to their friends and family members.”
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Code Reader
A code reader is a slightly lower-tech version of the scanner. It also plugs into the OBD-II port, but instead of performing a full service diagnostic, it will simply give you a numeric error code. It’s up to you to check that code against an online database or manual.
A code reader is a great car diagnostic tool for when you’d like something more helpful than a plain Check Engine light, but don’t want the detail or expense that comes along with a full scan tool.
For a good overview of what exactly a cod reader delivers and what differentiates a code reader from a scanner, refer to this informative article: Using a Diagnostic Car Code Reader.
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Multimeter
Multimeters can help you diagnose problems in your car’s electrical system. By measuring current, voltage and resistance, they can help you identify problems like faulty circuits, a bad battery charge and sensor issues.
“My multimeter serves me every day by determining whether a dead battery requires replacement or simply needs charging,” says Gelfand. “A multimeter also helps users check fuse integrity, verify power delivery to components and monitor electrical ground connections.”
Multimeters are affordable, and every DIY garage can use at least one. One quick tip: get a unit with a large digital readout, which will be especially easy to read during car diagnostics. And for an extra clever diagnostic trick, here’s how to test for corrosion in your car’s water pump, radiator or heater core with a multimeter.
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Non-Contact Thermometer
It’s no secret that engines get hot while running. But each part of your automobile is designed to operate within a certain range of temperatures. When something is going wrong, such as a build-up of friction or restricted air flow, then things start to get very hot very fast! To find out if this is the case in your car, use a non-contact infrared thermometer. This handy tool will allow you to check the temperature of hard-to-reach items, or areas that you shouldn’t touch while the engine is running. Use the thermometer when you want to check for break dragging, or a failing thermostat – both issues that can cause your gas mileage to plummet. And if you’re looking for more car diagnostic tools to help get better mileage, Family Handyman has you covered!
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Vacuum Pump and Pressure Testing Kit
Your car’s engine is full of parts that operate using vacuum pressure, and a vacuum pump and pressure testing kit will allow you to test these vacuum lines for leaks. Whenever you have concerns about a vacuum line deteriorating, simply break out these tools. Just remember to use the pressure testing kit after your engine has warmed up to operating temperature in order to get accurate readings.
Even better, this tool isn’t just for running diagnostics. Your vacuum pump will also come in handy for projects like changing your transmission fluid.
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Fuel Pressure Gauge
Has your car been feeling a little sluggish lately? If so, there may be an issue in the fuel system. Debris, leaks and other potential problems can all cause a drop in fuel pressure, resulting in reduced power. With a fuel pressure gauge, you’ll be able to tell whether your engine is getting the fuel it needs to perform properly.
If you do find an issue in your fuel pressure, get it repaired ASAP. To prevent future issues, one surprising trick is to never drive on less than a quarter-tank of gas. Want to know why? It’s all explained in this Family Handyman article: 15 Things You Should Never Do To Your Car.
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Circuit Tester Light
A test light functions as a down-and-dirty multimeter. It simply connects to a circuit and illuminates the light bulb if it gets power. The beauty of this tool is that it’s a simple binary: it either lights up or not. This makes for quick work of checking circuits. However, this simplicity is also this tools drawback. A test flight light confirms the circuit is working, but it doesn’t tell you any additional details such as the amps or volts, etc.
If you’re in the market for a test light, be sure to get an LED model, rather than one with an old-school incandescent bulb, to lower the risk of damage to your car’s computer.
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Mechanic’s Stethoscope
There’s a long tradition of car owners trying to describe those strange shakes and rattles that always seem to mysteriously disappear when the car is brought into a mechanic’s shop. One of the easiest ways to narrow down the source of those troubling noises, a mechanic’s stethoscope is a specially modified version of the medical tool.
For a good overview of a traditional mechanic’s stethoscope, see How to Diagnose Car Problems with a Stethoscope. But, car diagnostic tools continue to evolve, and wireless technology allows the modern mechanic to monitor these stethoscopes even while driving.
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Telescoping Mirror
Modern engines are miracles of compression as it seems like every year auto manufacturers manage to pack more items in a smaller space under the hood. This may be some impressive engineering, but it can cause a real headache for the DIY mechanic. One simple car diagnostic tool that will allow you to see hard-to-find and harder-to-reach areas on your car is a telescoping mirror.
Simple but dependable, telescoping mirrors work great with telescoping magnets to find out if that troublesome rattle is nothing more than a loose screw bouncing around with each bump in the road.
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Proper Lighting
We started this list with one of the most advanced car diagnostic tools available, and we’ll end with the most basic: effective lighting. It’s hard to fix what you can’t see, and even the most useful of tools are useless if you’re missing something obvious because of poor lighting. One of the best things you can do for your garage or shop is to invest in quality, reliable, adjustable lighting. It doesn’t need to be expensive, but it does need to be there. One example is this under-hood light kit.
FAQ
Why should I have diagnostic tools for my car?
Being able to diagnose what’s wrong with your vehicle can save you time and money by enabling DIY repairs, helping you detect problems earlier and improving your overall vehicle performance.
“These diagnostic tools empower you with knowledge and give you control over your repair choices,” says Gelfand. “I have observed multiple customers avoid pointless car repairs through their ability to identify the actual cause of their problems.”
How do I know if a code is serious?
Most modern scanners will have a severity rating on the code, either advising immediate attention or recommending you simply monitor the situation. For example, if your check engine light is flashing, then it’s serious enough that you should stop driving, or risk catastrophic damage. But if your check engine light is solid, you usually have some time to fix the issue.
When you’re using a diagnostic scan tool like an OBDII, you’ll receive a code that starts with a letter and is followed by four numbers, says Watson. The letter options can be: B for body, C for chassis, P for powertrain or U for network communications.
“That first letter tells you what part of your vehicle is having the problem, with the powertrain generally being the most serious, as it involves your engine or transmission,” says Watson. “If you receive a code that you’re unsure how to fix, the internet offers a wealth of car resources,” one of those being Bosch’s Autoblog.
About the Experts
- Elizabeth Kerstetter is a computer engineer and the co-founder and CEO of OBD Experts, a company that provides OBD software to telematics device suppliers around the world.
- Duane “Doc” Watson is a technical trainer at Bosch Mobility Aftermarket. He has more than 45 years of experience in automotive repair, has trained thousands of technicians and earned many industry awards, including Chevrolet Technician of the Year and Buick Service Master of the Year.
- Alan Gelfand has been the owner of German Car Depot for more than 30 years. His business is an independent automotive service center in Hollywood, Florida, specializing in the service and repair of German vehicles.
