I have a 2006 CTS 2.8. I have replaced 3 or 4 coils in the last couple years during the 140,000 miles traveled.

It started running rough again yesterday and the check engine light started flashing so I stopped by O'Reilly Auto Parts and then Auto Zone to confirm my suspicions.

It showed 3 codes that were duplicated, or 6 codes. P0300, P0303, and P0306.

I have replaced coil # 6 twice, the last time about 4 months ago.

I thought I will buy 1 coil at Auto Zone and replace #6 because I can get to it without taking off the plenum. I replaced #6 drove to Autozone thinking the replacement coil didn't seem to hep and found out that it reported the same 6 codes as before I replaced #6.

I am not sure what the heck is happening here. Can the wires going to the coil go bad?

What do I do next?

Thanks, Paul