Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Don't just post trouble codes in your repair questions, include the definitions!
Example: "My truck has these codes: p0101, p0336, p0405. Don't know where to start, thanks!"
If your help request contains a list of trouble codes without the definitions, there's a good chance I'm not going to bother looking them up and will just read the next post.
If you really want help, you need to give us all the information you have available to you, that includes the definitions of the trouble codes you need help figuring out, the tests you have all ready performed and accurate description of the symptoms.