Best Car Code Readers and Scan Tools

In 1996, On-Board Diagnostics/2nd Generation (OBD-II) diagnostic systems became standard on all vehicles. OBD-II identifies problems with the drivetrain and other mechanical or electrical components and systems, making driving safer and more pleasurable.

Specifically, OBD-II generates diagnostic trouble codes (DTC) and activates the check engine light (CEL), malfunction indicator lamp (MIL) or other warning lights. That’s where code readers and scan tools come in. A code reader identifies the DTC, but a scan tool does more. It may also tell you what the code means and what’s causing it.

“We’ve all been there, feeling stressed, not knowing what’s causing the problem. This is where a code reader helps—it lets you see the specific diagnostic trouble codes that pinpoint exactly what system needs attention,” says tech expert and engineer Robert Johns. “During my time in the industry, I relied on code readers a ton to diagnose issues. When something goes wrong, the computer stores a diagnostic trouble code corresponding to the faulty part. The code reader shows you these codes so you know precisely where to focus your diagnosis. It also erases codes to turn off the check engine light after repairs.”

Do I Need a Code Reader or a Scan Tool?

If you enjoy working on your vehicle or just want to avoid expensive diagnostic fees (like paying $50 to $100 to be told you have a loose gas cap), a DTC code reader or scan tool makes an excellent investment.

Code readers and scan tools plug into your vehicle’s 16-pin universal Assembly Line Diagnostic Link (ALDL) connector, interfacing with your vehicle’s OBD-II system. Code readers are typically reasonably priced, easy to use, read/clear DTCs and reset the CEL.

Scan tools cost more than code readers. They provide abundant, valuable information to help you quickly pinpoint problems code readers can’t.

What to Look for in a Code Reader/Scan Tool

Code readers offer a place to start when diagnosing a check engine light. Any number of issues can trigger a single DTC, so code readers are less helpful than a scan tool. “Code readers work well for general troubleshooting and simpler fixes since they’re affordable and user-friendly,” says Jones. “But sometimes a full scan tool is better, like if you need live data, module-specific work or repair verification.”

Besides reading/clearing codes, a scan tool can read live sensor data, beneficial when diagnosing a CEL or other car troubles. Using a scan tool as part of your regularly scheduled maintenance ensures your emission system is operating properly, increases fuel economy and even reduces repair and maintenance costs.

Here’s what to look for:

• Storing and playing back live data: Allows you to test drive your vehicle, and then review specific sensor output readings.
• Graphing data: Displays how sensors and data change over time and conditions.
• Displaying pending codes: When the OBD-II system has “seen” a one-time failure but has not turned on the CEL.
• Providing trouble code definitions and troubleshooting procedures: Understanding what the code means and what may be causing the problem, then guiding you through the diagnostic steps, are great features.
• Readiness monitors (I/M) status: Checks if a vehicle’s engine control module (ECM) has successfully completed the emission (smog) control systems I/M self-test.
• Compatibility: Ensure the scan tool or code reader can be updated and is compatible with multiple-year, make and model vehicles—especially yours.
• Service resets: Resetting things like the oil life system, electric park brake (EPB), tire pressure monitoring system (TPMS) and bleeding/flushing the anti-lock brakes system (ABS) saves a costly trip to the repair shop.
• Bi-directional: This allows you to send commands to test a device’s functionality after servicing, as well as reading data to verify repairs.

These scan tools and code readers are NOT for use on hybrid or electric vehicles.

Not everyone needs the most comprehensive scan tool available. If you’re just troubleshooting your family’s vehicles to avoid expensive diagnostic fees or keep your vehicles roadworthy, take a look at these scan tools and code readers.

The Best Car Code Readers and Scan Tools

• Best Bargain Code Reader/Entry-Level Scan Tool: Ancel AD310 Code Reader, Autel ‎MaxiLink ML629 Scan Tool
• Best Bluetooth Scan Tool/Code Reader: VeePeak OBD Check BLE+
• Best Value Scan Tool: Launch CRP129X Scan Tool
• Best Features Scan Tool: Foxwell OBD2 NT624 Elite Scan Tool
• Best Overall Scan Tool: Launch CRP129E Scan Tool
• Best Bi-Directional Scan Tool For Experienced/Advanced DIY: 2024 Model Launch X431 V Pro 4.0