Get all that sorted. Clear the codes and see what happens.
Low voltage will be sent to the ECM via the injection feedback wire. It can be caused by a few things.
Move one of the coils to another cylinder not affected. If the fault stays in the same location take a look at swapping the plugs as well. Would pay to take a good look at them.
There could be faulty plugs, faulty coils, faulty wiring, faulty connector, bad earth.
On that, remove that banks earth on the cylinder head. Clean the bolt thread with a little brass brush, give the surface of the head a clean with it. Spray some Deoxit or CO Contact cleaner into the thread on the head. (Make sure the engine is cold first) Clean the contact surface of the harness eyelet and retighten it all up nice and snug. Don’t over do it. It’s a steel bolt going into softer aluminium after all.
