1345 and 1347 are missfire codes with cat overheating and possible failure.
1620 is not listed
171,174 are lean codes
313 is a missfire in the first 1000 rpm and that is a coil.
300 is a random missfire
you did the plugs but there is a lot more.
Compression test, vacuum leaks, clogged injectors, coils, mass air flow are among some of the possible issues
Roy
Monday, April 1st, 2013 AT 12:41 AM