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Best Car Diagnostic Tool of 2021: Scan for Fault Codes

You may be baffled when a diagnostic indicator lights up on your dashboard. There are lots of warning lights these days and some, like the scary “check engine” light, don’t even tell you what the problem is.

If that describes you, your immediate reaction is probably to get the car to a repair shop as soon as possible.

“Car people,” however, know what to do when diagnostic lights turn on, and if they have enough information about their car’s problem they can usually fix whatever’s wrong. Those are the people who really need a car diagnostic tool, because among many other things, it lets them crack the code of that mysterious “check engine” light.

Modern onboard diagnostic tools (OBD2 scanners, for short), connect to a car’s computer system, read error codes and access specific data, letting the user see what the exact problem is so they can take care of it.

The Best Car Diagnostic Tools

1. Actron Elite Diagnostic Tool

The Actron is a perfect car diagnostic tool for those who do a good deal of work on their car, but don’t plan on opening a garage anytime soon. It’s very reasonably priced (at the bottom end of the price range for a full-featured OBD2 scanner), and offers strong performance and a wealth of valuable features.

Not only does the CP9690 read codes for all 1996+ vehicles, but it is able to handle OBD1-compatible GM, Ford, Chrysler and Toyota cars dating back to 1984. As a scanner and not just a code reader, it lets you view, record and playback real-time, historical and freeze-frame data details from just about any vehicle still on the road.

It also has a wealth of features you’d normally see on higher-end models, including dual PID graph capability, and battery, emissions readiness and O2 status. And just as impressively it includes “CodeConnect,” which is a database of more than 26 million verified fixes for “check engine,” airbag and ABS issues. Code definitions are displayed on the large, backlit LED screen, it can retain data from the last five vehicles scanned, and it’s compatible with any PC. As you’ve probably guessed, this is one powerful car diagnostic tool for the money, and the best of the bunch for automotive DIYers.

2. Launch PROS Mini Bi-Directional Scan Tool

The Launch PROS is hand-held, yet provides nearly all of the functionality you’d find on a huge free-standing unit costing thousands of dollars.

The X431 handles all of the usual OBD1/OBD2 scanning functions, of course, including viewing live, historical and free-frame data. But its bi-directional capability lets you access, diagnose, reset and instruct just about every system in more than 150 different vehicle makes and 10,000 models. A small sample: cycling the A/C clutch and fuel pump, gear, SAS and TPMS resets, ABS bleeding, resetting the brakes, evaporative emissions leak testing, altering configurations when components are replaced, key coding – the list goes on and on.

This small, powerful tool is Bluetooth-enabled, it can be updated to new software versions via WiFi for two years and it comes with a five-year warranty. Quite honestly, the Launch X431 is an amazing tool, for a price that’s way below what you’d expect to pay for its functionality.


If you’re not ready to lay down big money just to deal with “normal” car maintenance and repair issues, the Foxwell NT301 is a nicely-priced car diagnostic tool that will let you do all of the less-intensive but necessary detective work for under a hundred bucks.

Even at that price, it lets you read error codes; access live data graphs, logs and freeze frames; locate bad O2 sensors; check emissions readiness status; and of course, turn off the “check engine” light after you’ve figured out what’s wrong. Once you have an error code, it will display available definitions for the code with the push of a button.

This is a small but user-friendly scanner with a color screen and easy-to-understand keypad with hotkeys, it can send all results to a printer so you can take them to your mechanic if you’re in over your head, and it includes free lifetime software updates.

You can’t do things like check the battery status or do charging tests, deal with airbag problems or the ABS system, or reset the oil service light with this Foxwell, but it’s a great tool for the lower-level issues most of us run into sooner or later.

4. ANCEL Diagnostic Tool

Here’s our budget pick, and for its low price you’d expect that it’s only a code reader. It’s not, it’s actually a scanner tool and a very good one for what it’s designed to do.

It will read all of the OBD2 codes that much more expensive car diagnostic tools can read, it can pull up code definitions on-screen, allows you to see live, recorded and freeze frame data, reset the “check engine” light and do an I/M monitor readiness test.

This is another easy-to-use handheld monitor without a lot of bells and whistles, and without the capacity to more detailed testing, diagnosis or resets. But bear in mind that many repair shops will charge you $100 or so just to plug in a diagnostic tool and read error codes before actually doing any work on your car. This small OBD2 scanner only costs about one-third of that price, and can more than pay for itself the first time that dreaded indicator light turns on.

5. BlueDriver Bluetooth Pro Diagnostic Tool

A handheld car diagnostic tool is fine for a one-time check or for quickly resetting a dashboard indicator. But if you’re going to be doing more in-depth diagnosis work, having to stay plugged into the car’s OBD2 port can become a pain. The LSB2 provides a more convenient alternative: plug in the sensor, and use your phone or tablet to read any results or send any commands.

This BlueDriver comes with the sensor and an app that’s compatible with any Android or Apple device; you’re able to use the app to control the sensor, view live, recorded and freeze-frame data, access millions of suggested fixes for various error codes, and save all data directly to your phone. It’s not a bi-directional unit (not surprising, at a price less than $100), but it’s able to do many of the full OBD2 scanner diagnostics you’d expect.

There is one drawback to the LSB2: it can be slow. The connection can lag, interrupting the transmission of live data and ruining the test underway, and downloading the database of codes and suggested fixes can take a very long time. It’s a cool and convenient unit, however, and is a good alternative for more simple, repeated testing.

What to Look for in a Car Diagnostic Tool

car diagnostic tool

The proliferation of car diagnosis tools has made life much easier for auto repair professionals – and for home mechanics. These tools make it easy to know what’s wrong with a car – or at least get a good idea on where to start looking – when the “check engine” light comes on. In short, connecting one of these tools to a car provides human-readable data from the car’s onboard diagnostic systems.

There are two major types of car diagnostic tools, known in the industry and to some consumers as OBD2 (or OBD II) units. We’ll look at them very shortly. However, don’t confuse either of them with the tool’s predecessor, the OBD1 system, which was rather rudimentary and is only used today to diagnose cars built before 1996.

Read More: The Differences Between OBDI and OBDII

Even more limiting, each manufacturer’s cars require a different OBD1 tool. Starting in 1996 the technology was standardized, and all American cars manufactured since then can communicate with OBD2 scan tools. (In the EU, cars made in 2001 or later have the same capability.)

Types of Car Diagnostic Tools

The car diagnostic tools we’re discussion here fall into two basic categories: code readers and scan tools.

Code Readers

These are lower-level, relatively-inexpensive OBD2 devices which are able to read (and clear) most basic error codes from the car’s onboard diagnostic system. They cannot, however, read codes which are specific to manufacturers or vehicle models; this is sometimes referred to as being able to read “P0” codes but not “P1” codes. They also can’t display the data that’s tracked by the car’s internal systems.

Scan Tools

These are more advanced and more expensive OBD2 car diagnostic tools. They can do everything a code reader can, as well as reading P1 codes. They can also show live data in real time, recorded data captured by the car’s onboard diagnostic system, and other advanced information to help in troubleshooting problems.

To put it in simple terms, if you only want to be able to do things like turn off the “low tire pressure” indicator, or get a general idea about what’s caused your “check engine” light to turn on, a code reader will usually do the trick. (With lower-priced OBD2 models, you’ll probably have to search the internet to find out what the displayed code actually means.)

If you want to do more in-depth diagnostic and repair work on your car, you’ll probably need a scan tool. Consumer-level models communicate in just one direction; in other words, you can get almost all of the information you’ll need from the car, but you can’t send information back (except to reset some indicators). Pro-level OBD car diagnostic tools provide bidirectional communication so they’re able to instruct the car’s systems to perform self-checks, among other things. They will also run you at least $1500 or so, and can cost as much as $20,000.

Connecting Car Diagnostic Tools to Your Vehicle

obd2 port

Various models can connect to and communicate with your car in several different ways.

The most common method is via an OBD2 connector. Every car made since 1966 has a port specifically designed for this purpose, located near or underneath the steering wheel and often hidden behind a lower dashboard panel. Many scanners also allow connection via Bluetooth or WiFi to a PC, handheld phone or tablet, and some allow direct connections to laptops and computers as well.

Dongles that connect to the car’s OBD2 port and transmit wirelessly to computers are also becoming more common. These types of connections are sometimes meant to be permanent, because they transmit information to insurance companies with the goal of reducing premiums based on the driver’s habits and behavior.

If you plan on using your car diagnostic tool regularly, Bluetooth, wireless or direct laptop connections may be extremely helpful. Otherwise, they may simply be overkill.

Functions That Some Advanced OBD2 Scanners Can Perform

Budding mechanics (or budding Jay Lenos) may want their car diagnostic tool to handle some of the advanced functions necessary for in-depth troubleshooting and repairs. Higher-end devices can handle tasks like:

  • Detecting problems or failures in ABS braking systems
  • Testing battery current, voltage and performance
  • Taking freeze-frame shots of key readouts like speed, RPM, fuel consumption, coolant temperature and other metrics that can identify the cause of engine misfires; historical freeze frames can show you what was happening with your car at the exact time the “check engine” light turned on

In most cases, you won’t find a laundry list spelling out which of these functions a car diagnostic tool can perform. If you opt for a high-end model, it should be able to handle most or all of them.

One distinction which used to be important was the one between factory OEM models and aftermarket diagnostic tools, but over the years the difference has gradually disappeared. The majority of today’s aftermarket OBD2 scanners can do just about everything a more expensive OEM tool can.

Other Car Diagnostic Tool Features

One very handy feature available on some OBD2 scanners will be built-in (or Internet-accessible) access to a huge database of not only diagnostic codes, but recommended fixes for the problems the codes indicate. Some of these models will simulate emission tests and locate potential problems.

A number of OBD2 scanners will be compatible with at least some of the older cars outfitted with OBD1 systems. Some will reset airbag indicators once the airbag has been replaced, and there are models which can even program new keys to work with your vehicle.

One final consideration when buying a car diagnostic tool is how easy it is to use and read. Larger screens and bright LED readouts can make all the difference when diagnosing your car’s issues in a dark garage or in the driveway at night.

Final Thoughts

Many drivers wouldn’t dream of opening the hood of their car, let along trying to diagnose potential problems. After all, it’s not difficult to call your local repair shop or dealership and say “I’m bringing my car in tomorrow morning.” Having a car diagnostic tool, though, can be a big help for those who are somewhat mechanically-inclined, and has become an absolute necessity for weekend tinkerers or car aficionados.

Richard Reed
I've been a General Manager of a moving company and I've also been a Professional Mover for over 30 years. I've driven flat beds, reefers, dropdecks, moving vans, heavy machinery, etc. In my time as a Mover I've driven over 1,000,000 safe miles. My days of moving and driving truck are past me but The Vehicle Lab allows me to share the knowledge I've gained over the past 40 years.
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