No DTC with sensor disconneted

I tried to run an L92 with the wrong camshaft gear cover, and told me P0340 DTC (camshaft possition sensor). Problem was the cover leave the sensor to far to the new non vvt gear. Replace the cover with the lower profile one, and the code was not showing on again, but engine neither starts. Scan it several times with no results. BUT, I pulled out the sensor and neither shows any code. (ecu program remain untouched)

Why is not showing DTCs in that condition? I check with MAF, Coils, etc and only showed a code for water temp.