Diagnostic Trouble Codes

So many times we have customers that call in with “my truck has a code in it”.  As technicians, this is a pretty vague statement.  There are several things as technicians we can do to help customers when they call with a CEL light illuminated on the dash.

  1. How is the truck running?
  2. Do you have a programmer or scan tool that is able to pull the code?
  3. Is there anything that you have done lately that could be associated with the code?

diagnostic-trouble-codesBeing able to get a definition of a CEL light is fairly easy.  If you have a 1994 or newer Dodge if you use the key off-on cycle three times the code number will pop up in the odometer, or in the diagnostic center,  or on some of the early models there will be a flashing CEL light once you cycle the key three times.  On Fords and Chevrolets this is not possible.  So if the customer has a CEL light on these trucks and they do not have a programmer or scan tool that is able to pull codes, then what they can do is visit a local auto parts store.  Most auto parts stores will hook up to the OBD 2 port and will retrieve the codes for you for no charge.

Once you have retrieved your code and noted it, then we suggest to clear the code and see if it returns.  If it does, then it is a constant failure and not an intermittent one.

Now, you’ve retrieved your codes, you’ve verified weather they are constant or intermittent, you have defined the code, and now you’re ready to begin fixing the problem.  What do you do?

  1.  If you decide to tackle the code yourself then we suggest buying a manual for your vehicle or going to ALLDATADIY.com and purchasing a subscription for your vehicle.  This will allow you to define your code and get a “trouble tree” to fix the problem.
  2. If the code is basic like “low fuel pressure” etc. then changing a fuel filter or checking lift pump pressure will help to fix the situation.  Some codes are more complicated than others.

Click below for a list of codes we found most helpful for diesel engine troubles.

Chevy/GM Duramax Trouble Codes >>

Ford Powerstroke Trouble Codes >>

Dodge Cummins Trouble Codes >>


Leave a Comment