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Recently my car's check-engine light came on, I used a car OBDII port code reader to get the diagnostic-trouble-code (DTC) and then I googled what the DTC meant. I noticed that lots of the websites and searches are specific to a make (i.e. Mazda, Honda, etc).

Do car manufacturers provide specific make/model/year information for each diagnostic-trouble-code? Or is it only for make/model? or maybe only specific for the car make (i.e. Mazda, Honda, etc)?

If yes, where is this information officially published by the car manufacturer (is it on the car manufacturer's website or only available to dealers via some non-disclosure-agreement/agreement/special-access)?

It's hard to find good information about the diagnostic trouble codes when you get one on your car. So if there is some "official" documentation I can look up for my make/model/year then I want to find that... instead of some random website that has unverified/unknown-quality information/advice about something important (what is wrong with my car and how to fix the car).

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Some parts of the OBD-II code are the same for every vehicle (year/make/model independent), while others can be specific to a make and/or model. The year is usually irrelevant, though there has been some amount of change since OBD-II standards have been implemented. The website OBD-Codes.com explains the breakdown fairly well:

The first character identifies identifies the system related to the trouble code.

  • P = Powertrain
  • B = Body
  • C = Chassis
  • U = Undefined

The second digit identifies whether the code is a generic code (same on all OBD-II equpped vehicles), or a manufacturer specific code.

  • 0 = Generic (this is the digit zero -- not the letter "O")
  • 1 = Enhanced (manufacturer specific)

The third digit denotes the type of sub-system that pertains to the code

  • 1 = Emission Management (Fuel or Air)
  • 2 = Injector Circuit (Fuel or Air)
  • 3 = Ignition or Misfire
  • 4 = Emission Control
  • 5 = Vehicle Speed & Idle Control
  • 6 = Computer & Output Circuit
  • 7 = Transmission
  • 8 = Transmission
  • 9 = SAE Reserved
  • 0 = SAE Reserved

The fourth and fifth digits, are variable, and relate to a particular problem. For instance, P0171 code means P0171 - System Too Lean (Bank 1). To lookup your particular code, visit our OBD Trouble Codes section.

I've found OBD-Codes.com and engine-codes.com to both have a lot of good information on them. Not every code will be listed, but you can usually find the codes by doing a google search using the code itself (ie: P0171) and the words "OBD-II code" or something very similar. I'm sure that some of the manufacturers would sell you a subscription to get the information, but you'll find with the right Google-Fu you can find the information you are looking for ... or you can always come here and get an answer :D

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