The best OBD-II scanners are a must for any car owner, thanks to their ability to unlock the secrets of your car. It doesn't matter how laid back you are, a mysterious light on your dashboard is enough to make anyone an anxious wreck. Or maybe that's just me. Normally that would require a trip to the mechanic to decipher, but I know wouldn't want to spend my hard-earned money deciphering something that was never actually a problem.
Having an OBD-II scanner in your tool box can help you diagnose potential problems. That way you can figure out whether it's actually worth seeking professional help — or if this is something you can handle at home. The only problem is picking one. I am well aware of how intimidating OBD-II scanners can seem from the outside, and they're not all built equal. Thankfully we at Tom's Guide have spent a great deal of time testing various OBD-II scanners, to help you figure out the good from the bad.
Our current favorite OBD-II scanner is the Innova 6100P. Not only does this have the option to diagnosis problems with the handheld scanner or through the Innova app, it can actually predict potential problems ahead of time. There's even information on the kind of repairs and parts you might need, which made us feel more professional than any other scanner we've tested.
If you're looking for something as little more discreet there's the Bluetooth Topdon TopScan, which is completely wireless and is deceptively useful for viewing live data and diagnosing problems inside your car. But if you're on a budget there's the Launch CR529. It costs less than $40, but it's so feature-rich that it can outpace scanners that cost two or three times as much.
Here are our top picks for the best OBD-II scanners you can buy right now.
Tom is the Tom's Guide UK Phones Editor, covering everything from new hardware to the best mobile apps. He's also an avid electric car enthusiast, and will argue to the death in their defense.
The quick list
Here are the best OBD-II scanners you can buy right now, based on our own hands-on testing. You can scroll down the page to find more in-depth information about each mode, and what makes them so good at what they do.
The perfect OBD-II scanner to make you feel like a professional, this handheld scanner can do a lot more than read or diagnose faults. Paired with the Innova app it actually details what's wrong, parts you need, and how much it should cost. Plus predictive tools to warn you about potential problems in advance.
The easiest Bluetooth scanner to set up, based on our testing, while also offering a range of professional-feeling features in a into its compact design. That means you get diagnostics, repair instructions, parts lists and even predictive features to anticipate imminent problems.
Small and powerful, the Launch CR529 offers all the things you'd want from an OBD-II scanner — and some more high end features you won't find on like-priced rivals. Plus there's lifetime support and upgrades, making this scanner fantastic value for money
This might as well be a Nintendo Switch for your car's onboard computer thanks to its rugged horizontal case. But its' more that just a sturdy device, since built for professionals as well; as amateur drivers. It's one to consider if you want a powerful scanner than can handle a beating.
While capable as an OBD-II scanner, the Ancel BD310 can also be used to augment your car's dashboard with a range of engine specs. That's on top of a simple and elegant design, smartphone compatibility, and a very reasonable price tag.
The amount of use you'll get out of the Carly all depends on what kind of car you have, with VW, BMW and Ford cars getting the most out of the basics. Then again the Carly has one of the best companion apps we've ever used with an array of customization options and professional level tests.
What are the best OBD-II scanners?
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Best OBD-II scanner overall
The one thing that stuck out during my testing of the Innoa 6100P is that it really made me feel as though the job was being done by a professional. It doesn't matter how how much of an auto-amateur you might be, which is really rather miraculous.
How you ask? It's all thanks to just how the 6100P can get various diagnostic jobs done easily and quickly. You just need to get through the set-up first, which is, admittedly, a little more involved that other scanners I've tested. Not that I would call it difficult, since the scanner did fire up immediately after being plugged into my car's OBD port.
The best part is that the Innova 6100P is a hybrid model, letting you use either the bundled scanner or Innova's companion app — depending on your preference. The app itself also has an ingenious feature that can predict when various car components might fail, letting you plan ahead for future repair work.
Frankly, it feels like that alone is close to making the $120 price tag worth it. The fact that you can also get live data, read fault codes, run through pre-inspection I/M readiness checks and utilize the 72-inch data and power cable just feel like added bonuses.
Read our full Innova 6100P review.
Best mobile OBD-II scanner
Yes, I know, the Topdon TopScan doesn't look like much. But believe me there is a lot more to this compact scanner than meets the eye. This isn't just your average Bluetooth OBD-II module, beaming information from your car to the app on your phone. I was thrilled to see that it also goes well beyond the capabilties of rival scanners in its class.
There's more than just the ability to find faults and run I/M Readiness tests. Those may be important things to have, but the TopScan pushes the envelope further with its ability to check performance and efficiency. it can even go so far as to estimate your car's horsepower and torque.
There are OBD-II scanners that cost 10 times more without being able to perform checks like this. So whether you want to fine-tune your car or just make sure it stays roadworthy, this is one of the best things to have in your toolbox.
Read our full Topdon TopScan review
Best cheap OBD-II scanner
In my opinion, the Launch CR529 might well be the best value OBD-II scanner available. Not just because of its $38 price tag, but also because of the level of diagnostic features you're able to get for that price. I was not expecting to get quite so much for such a low cost.
There are some compromises you need to contend with for a scanner that's this cheap. Like the fact it can't use car manufacturer's specialty codes or that it felt pretty heavy in my hand. But it does still offer live data, an instant inspection feature and a surprisingly in-depth look at the inner-workings of your car. Better still the lifetime updates mean you should be able to keep using this scanner for quite some time — no subscription necessary.
I'll admit, the CR529 may not be suitable for those of you with a more professionally-minded attitude to cars. But the rest of you? You could do a lot worse than have this in your toolbox.
Read our full Launch CR529 review
Best OBD-II scanner for older cars
Best Pro-level OBD-II scanner
Topdon's Phoenix Lite 2 scanner is a pricey bit of kit, more than several other perfectly capable OBD-II scanners, but you are getting an awful lot for your money. Least of which is a scanner than is an ideal fit for amateur diagnosticians and professional mechanics alike.
The best part of that The Phoenix Lite 2 is completely wireless, with the control pad connecting to a Bluetooth receiver that plugs into your car's OBD port. That allows unparalleled movement around the car. The scanner itself is bulky and heavy, but it does offer a kickstand and rugged design that should let it survive any workshop environment.
There's also live data graphing, fault information, and a bunch more advanced items that most cheaper scanners can only dream of. Just be aware that you only get 2 years of firmware updates, after which you'll have to pay an extra $495 a year.
Read our full Topdon Phoenix 2 Lite review
Best dual-purpose OBD-II scanner
Ancel's BD310 is a dual-purpose scanner capable of operating as a standard handheld, and when connected to a smartphone via Bluetooth. Better still, it's capable of turning into a secondary display displaying various key engine details inside the cabin.
We found that the BD310 was one of the easiest scanners to keep around, because it's small and light enough to fit inside your glovebox. Granted this means the 2-inch display feels a little small, and we found the four-key interface to be a little awkward, but it didn't get in the way of figuring out how to diagnose your car.
The 56-inch cable is perfect to hanging over the hood while you work, and all BD310 itself is capable of performing action like an I/M inspection-readiness test or divulging performance details — including coolant temperature, engine timing and engine speed.
Read our full Ancel BD310 review.
Best companion app
The Carly OBD Scanner offers a lot of great features for your money, and we were particularly impressed with the quality of the companion app. While some Bluetooth scanners offer a pretty basic app experience, Carly has one of the best apps we've ever used.
Not only is it capable of fixing lights and diagnosing problems, it also features repair help to get your car back on the road, and tools to check that used car you're interested in isn't a lemon. Plus there's lifetime warranty, which is pretty rare but always appreciated.
The downside is that not all of the myriad of features available work with every car model. So you're going to need to check just how compatible your car is before you buy. Likewise, as good as the app is, you have to maintain an active subscription if you want anything more than basic OBD features — which can get pricey if you're not careful.
Read our full Carly OBD scanner review
Other OBD-II Scanners We've Tested
The Innova CarScan Mobile 1000 is one of the most innovative Bluetooth OBD-II scanners we've ever tested. Not only is it the easiest wireless OBD-II module we've ever set up, it also packs in a lot of the same incredibly useful and innovative features you'd find on larger Innova scanners.
We found that the CarScan Mobile 1000 offered a huge range of diagnostic features, including Innova's predictive software that can identify potential problems before they go wrong. Better still it has the same part and repair suggestion features, so you know exactly what to ask your mechanic for. On top of that, if you want the scanner to turn your phone into a second set of automotive gauges, that is an option.
Read the full Innova CarScan Mobile 1000 review
The ThinkCar ThinkDiag TKD01 is one of the largest Bluetooth-based OBD-II scanners around, which can make it difficult to install. In fact the 3+ inch size means some cars may need to rely on an extension cable to plug this scanner in. But the upside is that the bulk makes the oval-shaped module more or less indestructible.
ThinkDiag's app offers profiles fore more than 100 automakers, which makes it ideal for locating manufacturer-specific error codes. This scanner is also able to show extended fault codes and can deal with errors like the oil-change light and monitor key car systems with minimal fuss. Like Innova the scanner is also able to predict when future problems may arise, but sadly doesn't offer any advice on how to deal with the issue.
Just be aware that your profile is only free for a single year, after which you'll need to pay an annual subscription fee of at least $40 to retain access.
Read our full ThinkCar ThinkDiag TKD01 review.
Autel's Autolink AL539 has a feature you don't often see among OBD-II scanners: A built-in multimeter that can uncover problems in your car's electrical systems. That includes burnt-out cables, electric shorts, alternator voltage, busted fuses and so on. The only major downside is that you can't use the multimeter while the AL359 is plugged in as an OBD-II scanner.
As an OBD-II scanner, the AL539 is able to show a range of live data, while also offering the ability to run a comprehensive pre-inspection readiness text. Any faults that are uncovered are displayed with red, yellow and green colored lights — green obviously meaning everything is a-ok.
The design also offers a great many benefits, particularly thanks to the compact and lightweight frame. However the AL539 also has a pull-out stand, which lets it stand on its own, and a generous 58-inch cable. We also found the interface to be very easy to follow, particularly thanks to the icons for all the major functions.
Read our full Autel AutoLink AL539 review.
How to choose the best OBD-II scanner for you
If you're looking for insights into how your vehicle is working or what's wrong under the hood, there's no better way than to plug in one of the best OBD-II scanners and read the results.
After all, it's how your car dealer or repair shop would figure out what's wrong with your car when you drive (or are towed) in. Why shouldn't you have the same information?
OBD-II/EOBD scanners work on almost all passenger vehicles sold in the United States since 1996, in Canada since 1998, in the European Union since 2004, and in Australia, Mexico and New Zealand since 2006. If you're unsure where an OBD-II scanner plugs in, gere's how to find your car's OBD-II port on North American cars. If you're living elsewhere, here's how to find your OBD-II/EOBD port worldwide.)
Not all the best OBD-II scanners are created equal. There are two general types of devices.
Handheld OBD-II scanners come with their own screen and cable to plug into the car's OBD port. Wireless OBD2II scanners plug into the port, but then connect via Bluetooth to a smartphone or tablet to display their findings.
Whichever type you choose, there are several high-performance OBD-II scanners that cost less than $200. A couple are less than $30. What's important to remember is that the best OBD-II scanners provide the right mix of size, weight and the ability to read your car's fault codes and live data. The most important criteria are:
- Easy setup. If it takes forever to set up the scanner, you probably won't use it to diagnose a problem early.
- Faults and explanations. The best OBD-II scanners not only tell you the faults your car has but also can explain the meaning so you can either fix it yourself or tell a mechanic.
- I/M Readiness check. A good scanner will run the major engine and emissions tests to see if you'll pass your state's inspection.
- Accuracy. A scanner is worthless if its results aren't accurate, because the only thing worse than no information is incorrect information.
- Size and weight. If the scanner is heavy and bulky, chances are it'll stay in your toolbox and not in the car to help you on the road.
- Live data. By tapping into the car's engine speed, timing and other parameters, the right scanner can help track down an intermittent problem.
- Graphs. Numbers are good, but a visual representation of it is much better, particularly if you're comparing before and after.
- Warranty. You expect your car to last at least eight or 10 years, so why shouldn't your OBD-II scanner? That said, the best offer a lifetime warranty that should outlast your ride.
There's a gas tank full of criteria used to determine which OBD scanner is the best one for you. The most important is whether you want one that connects with your phone or tablet's screen over Bluetooth or a handheld unit with its own display and cable.
Next, think about longevity and get one that includes lifetime warranty or software updates so the scanner will stay current with changing automotive tech.
Then, how about screen size for a handheld scanner? Get the biggest, brightest and easiest display to read that is icon based for easy changes. If you're clumsy, look at rugged scanners with rubber bumpers to absorb the shock of being dropped.
Look for extras that are included on some models, like an electrical multimeter, the ability to read a manufacturer's proprietary codes or export documents as Acrobat PDF files.
Finally, the price for these sophisticated devices is right on par with professional-level scanners that are available for under $100. That's barely an hour's labor for a qualified mechanic, making it a win-win purchase.
How we test OBD-II scanners
To test the best OBD2 scanners, I used my 2014 Audi A4 Allroad vehicle while it was in the garage or on the road over a period of several weeks. After connecting each scanner to my car's OBD-II port, I made sure they could report the car's vehicle identification number (VIN).
For the wireless scanners, I connected to my Apple iPad Pro, Microsoft Surface or Samsung Galaxy S9+ phone via a Bluetooth or Wi-Fi connection. The handheld scanners only needed to be plugged into the OBD-II port, which provides power.
Next, I measured the cord's length on the handheld scanners and the wireless range on the others. With the car running, I monitored the engine and other vital systems, and then disconnected the engine's oil temperature sensor.
Finally, I checked the details provided by the scanner, fixed the problem, turned off the check engine light and erased the error code.
Then I hit the road to see if the scanner could display operating data such as engine speed, timing and coolant temperature. I paid attention to whether the device reported the data as numbers, graphs or auto-style gauges.
Regardless of which OBD-II scanner you use, you'll need to crack its code. All fault codes have four numbers and a letter prefix:
- Powertrain (P)
- Body (B)
- Chassis (C)
- Undefined (U)
Of the roughly 5,000 diagnostic fault codes available, some are generic and apply to all cars, like air temperature and throttle position. For these, the numeric section starts with a 0. Others are specific to individual carmakers and represent either a special piece of hardware or a more in-depth analysis of the problem. These start with a 1.
For instance, if you get a P0098 code, chances are there's something wrong with the engine's intake air temperature sensor. By contrast, a Ford that displays a P1112 specialty fault code means that the intake air temperature sensor is reporting values intermittently and should be replaced.
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