Tested: Best OBD-II Scanners for 2023

Seeing your vehicle's check-engine light come on can throw a wrench in your travel plans. It can also feel a little scary: Does it mean your ride is headed for the scrapyard? Or is there a simple fix? Without an expensive trip to a repair shop, there's really only one way to find out: an OBD-II scanner.

In 1996, OBD (On-Board Diagnostics)-II became mandatory for all cars sold in the United States. OBD-II uses a port that allows communication with a vehicle's onboard computers, providing critical insight to mechanics and technicians on the internal workings of the vehicle. This is how the pros determine what's wrong with your car when that check-engine light mysteriously lights up.

These days, consumers can easily access this information, potentially saving hundreds of dollars on trips to the mechanic. Instead of paying a tech to plug an OBD-II scanner into your car and tell you what's wrong with it, you can take a look at the codes first—if you have the right OBD-II scanner.

But which one should you buy? There are huge price differences between OBD-II scanners, which can cost from less than $20 up into the thousands. As with most gadgets, the more you pay the more features you'll get. To help you decide which one is right for you, we selected a variety of OBD-II scanners at various price points and ran them through the Gear Team testing garage.

For this test, we omitted any wildly expensive scanners, as those are geared toward professional repair technicians. Instead, we focused on consumer OBD-II scanners meant for garage warriors like us, who just want to know what the error codes are—and what to do next.

Our Top Picks

Things to Consider When Shopping for an OBD-II Scanner

OBD-II scanners vary greatly in price, ranging from tens of dollars to thousands. During our testing, we came up with two unofficial categories: display and diagnostic OBD-II scanners.

Display OBD-II Scanners

Display OBD-II scanners simply show error codes. If you just want to read what the code is and see some limited vehicle data, these are the scanners to get. You'll have to do some research on your own to figure out what that code means—and to determine your next steps. Display scanners are cheaper and less complicated to use, but they may lack many of the handy functions that diagnostic scanners provide.

Diagnostic OBD-II Scanners

Diagnostic OBD-II scanners are serious auto repair tools, boasting far more diagnostic information than display scanners. They cost more as well. These are for DIYers who feel comfortable disassembling vehicular components and putting them back together. Diagnostic scanners offer advanced component and module testing, allowing deeper investigation into that pesky Check Engine light. Some even offer technical advice, common repairs, and Technical Service Bulletins (TSBs). If you find yourself wrenching on cars more than the usual garage gremlin, consider investing in one of these.

Other Considerations

Vehicles equipped with OBD-II typically have a port under the dashboard on the driver's side. They can be tricky to find, but they're always accessible. Some cars have them on the left side of the steering column; others will locate the port on the right side. To access the information in the port, simply plug the scanner in and turn the key on, without the vehicle running. You can start the engine, but there is a risk that whatever the reason for the Check Engine light, it could damage components.

A vehicle's error codes show as a five-digit Diagnostic Trouble Code (DTC). This code will display alongside a short description that may or may not make any sense to you, akin to someone simply saying their hand hurts when in reality their pinky finger is broken. The DTC will point you in the right direction, but it's up to you to investigate and unearth the real issue. A number of DTCs, typically those related to the powertrain, are common across all vehicles and can be read by any scanner. However, some DTCs, such as those for braking or chassis systems, can be automaker-specific, and you may need to investigate which scanners (if any) will communicate with your car's various onboard computers. Some even are capable of doing nearly everything a dealer can do, including some programming.

We also tested both corded and Bluetooth OBD-II scanners. Overall, we felt the interface and user experience were more accessible through Bluetooth scanners and their associated apps, but they did take longer to set up. With an app on your smartphone, further info is already in the palm of your hand. Meanwhile, the speed and simplicity of corded scanners were definite advantages. Which one is better? That comes down to user preference.

Our Test Vehicle

We wanted to use a common vehicle for this test to best evaluate compatibility, so we pulled in a 2005 Toyota Corolla owned by Gear Team tester Collin Morgan and set to work. The old beater had just rolled over 250,000 miles, so we were excited (and slightly nervous) to see what the scan tools would uncover.

How We Evaluated OBD-II Scanners

Knowing that there are different OBD-II scanners for different situations, we avoided pitting them all against one another. Instead, we decided which scanner works best for each situation and rated them on that metric. We took detailed notes on the capabilities of each and started our testing.

To manufacture a check-engine light, we unplugged the mass-airflow sensor on our Toyota Corolla, started up the car, and verified that the light was on. Then we simply plugged each scanner in and evaluated the following parameters:

• Time from plug-in to code display
• Number of live data Parameter IDs (PIDs)
• Number of freeze-frame PIDs
• Number of Inspection and Maintenance (I/M) Monitors displayed
• The quality of the user interface (UI) through an app or the scanner itself
• Accessible tests, smog-check capabilities, and additional diagnostic resources
• Cord length (if applicable)
• Other general notes

Comparing our notes from this test helped us choose which OBD-II scanner is best for various applications and which scanners don't quite live up to expectations. Here are our top picks for the best OBD-II scanners.