Best OBD2 scanners for 2021 – Roadshow [CNET]

Control electronics and computer chips, which have been an integral part of cars for decades, are as critical as any mechanical components for a car’s operation. Many of the mechanical systems in a vehicle are managed by a progressively complicated network of electronic controls and sensors. This is true whether we’re talking about the engine and transmission, safety features, suspension, brakes and emission controls, accessories or even tires. 

While this sophisticated system supports cars as they become more and more technologically advanced, having such a complex computer in your car is a double-edged sword — unless your a computer programmer, how on earth do you determine what exactly is tripping that dreaded “Check Engine” light? Enter an OBD2 scanner. This type car scanner is crucial for understanding, maintaining and repairing modern vehicles. DIY types or anyone who wants to know what’s happening inside their car — and possibly save a few bucks — can benefit from an OBD2 reader and a basic understanding of what to do about certain fault codes.

We encourage adding an OBD2 diagnostic scanner to your toolbox, but it can be intimidating to search for the right one. There are hundreds of different OBD2 scanner options out there in auto parts stores, discount stores and at the far fringes of the internet, with prices varying by thousands of dollars. Many are excellent, regardless of price. Many are junk, with no legitimate product support. 

This list includes an OBD2 scanner tool for every purpose and buyer, and it’s updated periodically. Keep reading for an overview of how scanners work, what they can do, our methodology for choosing them, key things to consider before purchasing and some pro tips.

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OBD2 car scanners 101

If this “onboard diagnostics” stuff sounds intimidating, the basics are actually fairly simple. It started in the 1990s, when the US government mandated that all vehicles beginning with the 1996 model year be equipped with a standard self-diagnostic system called OBD2 (for onboard diagnostics, generation 2), primarily to monitor emissions control systems. Since then, OBD2 has grown ever more sophisticated, monitoring ever more systems, but the process remains the same. When OBD2 records a problem, it creates a fault or diagnostic trouble code, then lights a warning on the vehicle dash (often that ubiquitous check engine light).

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Fundamentally, an ODB2 scan tool reads and reports those trouble codes. It plugs into the car’s diagnostic block, often called the OBD2 port — an easy-to-identify, trapezoid-shaped female connector, noted in the owner’s manual and typically located under the dash or near the steering column. Then it scans the OBD2 system to find the faults or trouble codes.

Now, those codes are in fact codes, or five-place alphanumeric designations. Code P0420, for example, means the catalytic converter is not operating properly. The most rudimentary OBD2 scanners still simply report the error code and you will have to check a reference manual or head for the internet to learn what P0420 means. But in 2020, the right, still modestly priced OBD2 scanner will tell you what the code definition is in English (or multiple languages) without having to look it up.

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OBD2 scanners are less expensive than ever, but competition makes the supply side of the market wilder than ever. Anyone who has carefully shopped for a mattress will understand. There’s a handful of established players, a bunch of upstarts and a vast expanse of noise. Even the respected companies will build essentially identical scanners with different model numbers and insignificant appearance changes to sell through different retailers (sometimes at different prices). Differences are sometimes hard to discern.

Depending on where you live and what you drive, a decent OBD2 scanner can pay for itself in relatively short order, if only through the fuel and time saved by avoiding trips to the local auto parts store for a free code read. OBD2 code readers don’t have to be expensive, but every car hobbyist or do-it-yourselfer should probably have one in the tool kit.

How we came up with our list

The list of the best OBD2 scanners above runs the gamut from the least expensive way to check engine trouble codes on your vehicle to excellent car enthusiast-type devices to a probably-too-expensive, full-professional mega scan tools. We evaluated reports from testing labs and scanned user ratings at popular shopping sites. We interviewed (harassed) experts, including Luke Daley at Innova and Jim Fish at BlueDriver, plus we applied personal experience.

Before you choose an OBD2 code reader, consider the following pointers. And before you click “Confirm Order,” have a look at our pro tips below.

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2. Which type works for you: Across the price spectrum, there are basically two types of OBD2 scanner. The dedicated hand-held scan tool is a self-contained device that plugs into the OBD2 port via cable (preferably long enough to reach from inside the car to the engine bay) and does its job. It has its own screen, buttons, software and computer chip.

The second type is a Bluetooth OBD2 scanner, known in the trade as a Bluetooth dongle. This type is usually a fairly small, plastic device that plugs into the OBD2 port and then connects to a smartphone or tablet via Bluetooth. Its job is to wirelessly transmit data from the vehicle’s OBD2 system to the phone, where that data is processed and presented by the dongle manufacturer’s control app. With a Bluetooth OBD2 scanner, the quality of its manufacturer’s software is paramount.

The primary advantage of the Bluetooth device, if it isn’t obvious: lower cost. Why pay for a screen and computer chip when your smartphone already has those? A Bluetooth OBD2 code reader dongle uses those components on your phone, where the screen and the chip are probably much higher quality than you need for this task.

If the typical cost advantage in a Bluetooth OBD2 scanner sounds like a no-brainer, you should consider the more subtle issues. Dedicated scanners are in important respects more efficient to use and if you use the code reader regularly to diagnose check engine lights, or for longer sessions, speed and simplicity matter. With a self-contained scanner, you never have to worry about the quality of the Bluetooth connection, your phone charge or the strength of your Wi-Fi or cellular signal (the typical Bluetooth OBD2 scanner relies on access to internet databases). You won’t be interrupted by incoming calls or notifications while you’re using it. A good dedicated scanner is more impact-impervious than a smartphone and drops are probably inevitable. What happens if your $1,000 phone falls in the engine bay and lands on the transaxle case, or gets wedged between a manifold and the engine block? Many Bluetooth scanners want to sell you upgrade subscriptions and some of the apps have ads.

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An OBD2 scanner is primarily intended to help figure out what might be wrong with a vehicle and then help get it fixed. It can reset certain parameters once the repairs are accomplished. More capable scanners can make finite adjustments in certain vehicle systems. An OBD2 scanner is not a flash programmer — a device that can actually rewrite the carmaker’s control code in search of more horsepower from the engine or different transmission shift points. Flash programmers are a thing, but they’re a different beast entirely and typically auto-brand specific.

Finally, when it comes to OBD2 scanners, don’t underestimate the value of product support. Even the most confident do-it-yourself folk will have questions about what the code reader might be telling them, or something that doesn’t seem to be working as it should. Beyond limitations noted in the list, the manufacturers of our best scanners should be able to provide answers to your questions and in reasonably short order.

Product support includes software updates. The reputable brands update their OBD2 scanner software regularly — at least once a year — so stay on top of it. The updates are usually easy to install, from a PC or over the air.

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Written for Roadshow by J.P. Vettraino.