Code Readers vs. Scan Tools

Both can read car codes, but which is best for which situation?

Both code readers and scan tools interface with a car's on-board computer or diagnostic system to identify or troubleshoot problems. A code reader is a simplified version of a scan tool, but it's only capable of performing basic scans of trouble codes. A scan tool can read and clear trouble codes, and it may also provide advanced data reading and playback features, knowledge bases, diagnostic procedures, and built-in testing equipment.

Code Reader vs scan tool

Overall Findings

Code Readers
  • Read, display, and clear car trouble codes.

  • Reset the check engine light.

  • More advanced or expensive code readers can read and display data, reset readiness monitors, or access parameter IDs (PIDs) provided by the onboard computer.

Scan Tools
  • Read pending, generic, and manufacturer-specific codes.

  • Provide troubleshooting information, tips, and trouble code definitions.

  • Record and play back live data.

  • Graph data or access specific parameter IDs (PIDs).

  • More advanced scan tools include diagnostic equipment like scopes and multimeters.

Because these devices are cheap and easy to use, code readers are convenient for car owners and mechanics who want to read and clear diagnostic codes. Scan tools are more expensive but can do everything a code reader can do, as well as provide troubleshooting tips, data readouts, and diagnostic equipment.

Professional automotive technicians typically require high-quality scan tools to work efficiently, while the average do-it-yourselfer should be able to get by with a cheap code reader or a nearby service willing to read codes for free.

If budget is your priority, take your codes to an auto parts store or shop. Many check and clear codes free of charge.

Code Readers Pros and Cons

Advantages
  • Wide price range makes for wide ranges of features and options.

  • Very affordable—many available for around $20.

Disadvantages
  • Not as advanced, accurate, or helpful as scan tools.

Most people can get by with the free code reading service offered by a local parts store or an internet search to find out what a trouble code means.

No two code readers are the same. While feature sets depend largely on price, any code reader can perform the basic task of reading, displaying, clearing codes, and resetting the check engine light in a car.

More advanced code readers can do the following:

  • Display trouble code names.
  • Read and display live data.
  • Display freeze frame data.
  • Display readiness monitor status.
  • Reset readiness monitors.
  • Provide basic access to the full range of parameter IDs (PIDs) provided by a vehicle's onboard computer.

Scan Tools Pros and Cons

Advantages
  • Sophisticated diagnostic and troubleshooting tool.

  • Some include advanced data reading and playback features, knowledge bases, diagnostic instructions, and built-in testing equipment.

Disadvantages
  • Very expensive—some cost several thousand dollars.

  • Steep learning curve.

Spending a lot of money on a consumer-grade scan tool makes only sense if you're a car enthusiast or DIYer with a small fleet of vehicles—not to mention a large budget.

Scan tools typically offer a suite of features depending on budget and intended use. Low-end, consumer-grade scan tools provide code definitions and basic troubleshooting tips. High-end scan tools include more in-depth diagnostic and troubleshooting procedures, and some have built-in testing equipment like scopes and multimeters.

Here are some of the things a scan tool can do:

  • Provide troubleshooting information or tips.
  • Record and play back live data.
  • Graph data or graph specific PIDs.
  • Read manufacturer or pending codes.
  • Utilize functions that require bidirectional communication.

Another option to consider is an ELM327 scan tool. These microcontrollers function as an interface between the car's onboard computer and a personal computer, which could be a smartphone, tablet, or laptop. These devices perform the duties of a basic code reader or an advanced scan tool.

Final Verdict

If you're wondering whether you should get a code reader or scan tool, start with a code reader. This way, you'll have the knowledge base without making a big dent in your budget. If you're a DIY or shade-tree mechanic, a basic code reader can handle the simple task of clearing codes and resetting a check engine light.