My truck has developed a rough idle / loss of power issue today on the way into work. The truck ran fine until I got caught in traffic trying to get in the gate and idled for roughly 15 minutes (COVID checks at the gate). I am getting the code P0351 Ignition Coil "A" Primary Control Circuit/Open. Can anyone help me track down a schematic so I can narrow down the Coil or bank I need to look into? I looked over the wiring on my lunch break and saw no obvious frayed wires or other damage.

The truck is a 2011 F150 5.0 roughly 110000 miles original COP's. Looks like it might be time for a replacement set. Spark plugs are NGK Iridiums with roughly 10000 miles on them. Are these trucks picky on what spark plugs you use leading to COP failure? Should I swap the plugs for a Motorcraft set?

Thank you for your help. First time posting to the forum but it has been a tremendous help in the past.

 

I run COPS until they quit. Haven't replaced one in 6-7 years (knock on wood). It's up to you if you want to go that route but it's my opinion that I have better things to do with my money. When I do a spark plug change, I do replace the boot and springs, though. Think of them like plug wires on an older system.

That said, a P035x code indicates an electrical circuit fault related to the #x COP. That means it could be a bad coil, a flaky connector, a PCM problem or a wiring harness fault.

1. Try reseating the COP connector first.
2. Swap the #1 COP with another easy-to-reach unit and retest. If the fault stays with that cop, it's bad. If it stays on #!, then it's one of the other items.