I hope someone can help figure out this issue for. I have a 2018 5.0, and after driving to a DR appt, I came out and used the remote start to get it going, I was maybe 100 ft away. The light wasn't on as I drove there, but when I got in the truck, the CL was lit up. I took it to a shop I used to have some wiring damaged from a squirrel, and that was months ago, but when he hooked up the OBD reader, he said it showed an old mis-fire code for cyl 1. He tried to clear it, but couldn't. Any ideas? I also am new to this brand of truck. I hear if you change a battery, things need to be reset. If I disconnect one battery terminal to reset the CL, will I only need to remove 1 terminal or both, and would I need to reset anything? Thanks in advance for any help.

 

If you try to reset a cylinder misfire code and it doesn't or return, I'll think you still have a misfire. Swap coil with another cylinder and see if it moves

 

But shouldn't the CL be able to be reset with the OBD reader since it's done without the engine running?

 

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Reset, yes.
As soon as you start the engine, and that cylinder does not work, it comes right back.
Clearing code never fixes anything that is broke.
The purpose of codes it to tell you there is a fault present.
Good luck.

 

Which is why I want to reset the CL. The miss-fire code that was found was an old one. And the fact a repair shop with the OBD reader which should be able to reset the CL, but was unable to, might be from other electrical issues from wire damage due to rodents, which was repaired only a few hundred miles ago. Just two weeks after the wiring repair, I had my truck stall with a message that said something about auto stop, which is disabled in my truck. It only happened once, but still, an issue from the wiring maybe? I'm trying to eliminate and isolate what ever issue is causing this.

 

Which is why I want to reset the CL. The miss-fire code that was found was an old one. And the fact a repair shop with the OBD reader which should be able to reset the CL, but was unable to, might be from other electrical issues from wire damage due to rodents, which was repaired only a few hundred miles ago. Just two weeks after the wiring repair, I had my truck stall with a message that said something about auto stop, which is disabled in my truck. It only happened once, but still, an issue from the wiring maybe? I'm trying to eliminate and isolate what ever issue is causing this.

 

There might be rodent damage in another area, or a new rodent problem. If it was me, I would first exchange coils to see if code transferred to new location. Sometimes people use junk aftermarket stuff that only lasts a short time.

 

I understand I know nothing of previous repairs. But my post also ask about the battery being disconnected and if I need only to remove one or both cables, and does it need to be reset as some threads I have read talk about this when new battery is installed?

 

It is my understanding disconnecting the battery for say 10 min. then momentarily touching a ground cable to the 2 disconnected cable ends will sometimes reset some codes but not all !! It also resets the adaptive learning curves etc.
As others have said swap coils & even plugs etc. & see if the mis-fire follows the exchange.......Usually not being able to reset a code should tell you a code is still present @ that particular location !!

 

If you have a persistent problem code that you can't clear, the most likely cause (by far) is that you still have the problem. Thoroughly troubleshoot that possibility before moving on to things that are much less likely.