Error Code P3400
My father in-laws truck is a 2007 GMC sierria and on thier way to our house his check engine light came on. We took it to Autozone and they read it. It showed a P3400 error, but they couldnt tell us what that error was in a GMC. They reset the code and it hasnt come back on yet, but we have only driven it a few miles so far.
Can anyone tell me what that code is?