Question: What’s the best/cheapest car diagnostic tool that actually works?
I have a decent amount of knowledge about cars, and I need to save a little money by diagnosing my own check engine light. I know I can rent or buy a scan tool from the local parts store, but I’m not sure if that’s going to get the job done. What’s the best scan tool I can get without spending more money than I’d spend at the mechanic in the first place?
Since you have a decent working knowledge of cars, you probably already know that there’s no real substitute for the car diagnostic tools that a professional diagnostic technician has at his or her disposal. Those tools, of course, typically consist of something like a Snap-on Modis and a whole lot of prior experience diagnosing similar problems. However, technology has come a long way in recent years, and there are still ways for a determined do-it-yourselfer to save some money during tough economic times.
Getting at the Codes
The simplest "scan tools" are really just “code readers,” and that may be what your local parts store tries to sell or rent to you. This type of scan tool tends to be very affordable, and it can get you on the right track, but knowing the trouble code is only the first step in a potentially long and complicated diagnostic process.
See more about: Car code readers
Live Data Streaming
In order to be a really useful car diagnostic tool, a scanner should have the ability to interface with the car’s computer and display live data. Some scan tools are only designed to show a long list of all the available data values, while others allow you to pull specific parameter IDs (PIDs) and create a custom list. That can be tremendously useful during the diagnostic process, since it allows you to watch for problems during a test drive.
You can find decent scanners that perform those functions for under a hundred dollars, although the cheapest option may be an ELM 327 scanner. These “scanners” plug into your OBD2 port and use an ELM 327 microcontroller to interface the computer in your car with a phone, tablet, or laptop via either a wireless or USB connection. If you have one of those devices already, then you should be able to buy some premium ELM 327 software and still come well under the price of a traditional scanner.
See more about: Connecting with ELM 327 Bluetooth
The Best Car Diagnostic Tools Include Diagnostic Procedures
The one thing that all “affordable” code readers and scan tools lack is the knowledge base that the best car diagnostic tools like the Modis come with. In addition to pulling codes and displaying data in a highly efficient manner, professional scanners also provide technicians with diagnostic procedures to follow in order to get to the root of a problems. In some cases, that includes specific procedures to test whether various components are in working order, which is the only way to avoid the “throw parts at it” method of car repair. Many shops also have access to programs like Mitchell and Alldata that also provide invaluable diagnostic flow charts and testing procedures.
See more about: Scan Tools Vs. Code Readers
Professional diagnostic technicians also have a wealth of personal experience to draw on, and no affordable car diagnostic tool is going to provide either that or the diagnostic procedures you’d get from a tool like a Modis or software like Alldata. Of course, that doesn’t mean you’re out of luck. Like it’s done in so many other areas, the Internet has proven to be a leveler in the field of automotive diagnostics. There are a variety of free (and paid) services available that you can use in conjunction with an affordable scan tool, like an ELM 327 scanner, to diagnose your check engine light.
The key thing to remember is that if you’re experiencing a problem with your car, somebody else has probably experienced it before, and he’s probably posted about it to the Internet. Our own Auto Repair site contains a wealth of troubleshooting information for DIYers, including solutions to many sticky diagnostic situations, so you might start there--after you’ve picked up the best car diagnostic tool you can afford.