DTC stands for “diagnostic trouble code,” usually a series of five letters and numbers (such as P0300) that tells automotive service technicians – aka mechanics – what’s wrong with your engine, emissions controls and other components according to your vehicle’s on-board diagnostics system.

The acronym also represents some BMW and Mini traction control systems, named Dynamic Traction Control.


Since 1996, technicians have plugged scanners into second-generation on-board diagnostics systems (OBD-II) to read codes that tell them what happened to cause the vehicle’s “check engine” light to come on or problems such as stalling, misfiring or engine knock. When something bad like that happens, OBD-II will store a trouble code to help the mechanic track down possible causes.

You can buy a scanner (probably for less than $100) that will show diagnostic trouble codes in your vehicle, but unless you’re experienced at diagnosing and repairing modern cars, the codes may not be too helpful. As the saying goes, a small amount of information is dangerous in the wrong hands, so most people are better off letting an experienced mechanic dissect the DTCs and do the repairs.

Learn more

Answered by Rick Popely on August 25, 2010 | Permalink

Search Results

Ask.cars.com Search Results for


See if your question has already been asked and answered

Thank You!

Your question has been successfully submitted to Ask.cars.com. It will now be reviewed by our editors and we'll answer it soon if we think it's a useful question. You will be notified via e-mail when the answer is posted. Ask.cars.com tackles your questions about new cars and the car-buying process. Unfortunately we can't answer questions regarding:

  • Used cars.
  • Most aftermarket products.
  • Mechanical issues. You can visit our friends at Car Talk to discuss your mechanical problems.
Thanks for your interest.


Have our experts answer any of your questions about new cars.

Email us at tips@cars.com

Maintenance Advice
Get answers from the
Car Talk Community