Car Terminology: Discussing DTC (Diagnostic Trouble Code) and DTC Readers

August 22, 2008

The days of playing “guess-what’s-wrong-with-your-automobile” is long-gone. With most of the vehicles today being a lot smarter through computerization and better technology, auto repair and vehicle troubleshooting has become easier and smarter as well.


These days, you’ll notice more and more auto shops using handheld devices or plugging your vehicle into a console that lets the read the information from your engine system’s onboard computer. Most of the time, mechanics today read the DTC that they get from your vehicle.

So what exactly does DTC mean?

DTC, as you can already surmise from the title, is an acronym for “Diagnostic Trouble Codes”. Today’s computerized engine control system can up to a certain point self-diagnose to detect auto problems that could be affecting your vehicle’s emissions and engine performance. This also goes for the onboard systems and the antilock brake systems controlled by your engine’s computer.

When your engine control system detects a problem, the computer stores the diagnostic trouble code in its memory. This is the time that the “check engine” sign lights up. There are some automobiles today that can activate its special diagnostic mode by grounding some terminals found on the diagnostic connector. Doing so causes your “check engine” and other lights to flash out the problem code. But for most vehicles, to obtain the diagnostic trouble code, all you have to do is plug-in a diagnostic trouble code reader (DTC Reader) or scan tool into the computer system.

Finding A DTC Scan Tool or Reader

If you’re nowhere near any fully-equipped auto repair shop then you’ll be glad to know that there are many companies offering Diagnostic Trouble Code Readers and scan-tools at economical prices. The most inexpensive variants should cost you just around $60. Of course, the more advanced the device is, the more expensive it tends to be. If you can’t purchase your own DTC reader, then another option is to rent one from a rental center or an auto parts store.

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