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Discription and break down of all OBD II trouble codes
I am posting this up on someone elses suggestion that it might be helpful to to others. If any one dosen't know OBD II was designed to be a kind of generic, system common to all vehicles in the US sold after 1996. This was to allow a certan standard accross the auto industry, to make diagnosis and repair easier, but primarally OBD II was put in place to control emissions more effectivly. At the heart of the OBD II system is 5 digit alphanumeric trouble code. The trouble code not only tells of a malfunction, but exactly where the malfunction is. I will now break the code structure for future trouble shooting of all OBD II vehicles.
The first part of the code is always a letter and can only be one of 3
P= Powertrain
B=Body
C=Chassis
The code will always start with one of the 3 letters above, never a combination just 1 starting letter.
The second digit in the code tells whether its a generic code, the same on all makes and models, or it is a code specific to that make and model. The second digit will always be one of the 2
0=SAE controlled code(generic to all vehicles)
1=Manufacturer specifc code to that make and model
The third part of the code makes up the meat and potatos of the code and consists of three digits in a row. The three digits tell specific system effected, compont effected, and sub compont effected, and always in that order. The larger more complex systems have 2 sets to cover all the specific parts of the system. The numbers proceed as follows
100=Fuel air metering system
200=Fuel air metering system
300=Ingition System Misfire
400=Auxiliary Emission Controls
500=Vehicle Speed/Idle Control System
600=Computer&Output Circuit
700=Transmission(Automatic Only)
800=Transmission(Automatic Only)
When a fault is detected usually the last two zeros of the above code will be diffrent to tell of compont and sub compont effected. For example when a misfire is detected the code will be P0302. This code effects the power train(P), its a generic code(0), ignition system misfire(3), cylinder #2 (0 and 2).
That is how the OBD II codes are formed and used for trouble shooting purposes. Also something to note is that these codes are diffrent from the codes on OBD I and cannot be used on OBD I cars due to the fact that there is no specific code structure to OBD I codes and the codes are diffrent on every car and some on the same car diffrent model year are diffrent. Hope this helps in the diagnosis of some of your OBD II faults in the future.
Last edited by TotalEclipse112 : 09-09-2005 at 01:19 AM.
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