P2237 Code still there

Can't get rid of this P2237 code on my 2009, I have read through many of the threads here.

The code comes back pretty much immediately after resetting, not like most other codes.

I have changed both O2 sensors, replaced with Denso. I changed the ECM, hoping that would solve it. Put in a used ECM from eBay, so I suppose it could have been faulty.

Is it time to start chasing wires? Any suggestions on fuses or relays to check? I appreciate any input.