I'm betting that code will clear up once you replace the coils and plugs.

 

That would surprise the carp out of me. 🤣

 

Keep us informed.

 

Odd that all three coils on one bank go bad at once?

The O2 sensor for that bank might be causing rich running and plug fouling, therefore misfires.

 

All four of the O2 sensors are good, they were replaced a couple of months ago. The error is P0051, which is not in the #*$$)!!@ service manual. Something about the control circuit being low.

 

Got the Delphi coils and plugs today. Too late to put them in but I will do that tomorrow.

The coils are made in China. <groan>

I also rechecked the connector from the sensor right behind cyls 4, 5 and 6. Everything is in perfect condition. No frayed wires, no breaks. Nothing.

 

Finished the replacements. The plugs needed changing. The coils were... Funky. Dirty. Some of the seals were worn and a little oil had leaked past them. The engine starts smoothly and the misfires are gone (once I remembered to plug in the #6 coil &#129315, but the P0051 is still there. Let's see if it goes away when I drive to work tomorrow.

 

See if you can clear it and try that at least two to three times if it returns. I've had that code pop up a few times before and it's always gone away eventually. I've never changed the O2 sensors nor cats (fingers crossed since I just posted that!!!!)

 

I have cleared it at least a dozen times and it always came back.

 

That before you changed the plugs and coils though?! Still, fingers crossed