Will bad ignition coils cause a CEL Code?

After doing some research I've narrowed down to a potential bad ignition coil. Recently the engine has had less power, cold starts takes a few seconds, sometimes theres a chirping noise (not a belt), and loss of power at higher RPM levels.

My car is a 2006
29K miles on the odometer

The thing is that a code hasn't come up so a buddy of mine thinks it could be something other than bad ignition coil. If it's possible to be a bad ignition coil without having a CEL code then I know it's the ignition coils.

 

Usually, you will get a CEL. Not always, though. Same goes for a failing cat converter.

You may want to check/ test them

edit: here is the link for testing coils https://www.rx8club.com/series-i-do-yourself-forum-73/diy-testing-all-rx-8-coils-gm-ls2-yukon-coils-sparkplug-wires-222641/

 

There isn't a bad coil code. A bad coil can cause the PCM to set other codes like missfire codes, Mixture codes or others.

 

If the cat is failing wouldn't it cause noises or vibrations? Because I don't have those issues so I'm assuming it's something else like the ignition coils. I had a P0335 and P0107 code come up after I seafoamed my car a couple weeks ago. The car ran great afterwards then in a week I have loss of power and cold starts take a few seconds. The P0335 code indicates the eccentric position sensor is bad which would also result in loss of power. I cleared out the codes today and will see if the P0335 code comes up again as that would mean the sensor is bad.

That tester you showed me should let me know right away if its the coils or not. Thanks for the link.

 

there are many symptoms of a failing cat. One way to check is to take the car for a spin, bring up to operating temp, then park and check under to see if cat glows. Or, pull it down (when cool) and visually check.

P0335

P0107

 

I actually read all of those threads over the past week before creating this thread. I try to do my own homework before asking for help.