Codes 63, 13 and 31

[RICHARD TILL]

Thanks in advance for any advise or comments. Several months ago i had a intermittent code 63 which is the right oxygen sensor. I swapped that sensor to the left side and got code 13 . Yesterday i replaced the left sensor with DENSO 234-3094 that i purchased from Rock Auto. Supposed to be an exact replacement. As soon as i started the engine the service engine light came on. This time its code 31. I have the ST-364-90PSID manual and it states that its the cam sensor. The manual said to probe ECM harness pin D3, crank the engine over and read the meter. Big mistake i guess but i didn`t do that. Gotta dig and find which wire on the brown connector D3 is. I skipped to connecting a test light between terminals A and C of the supply side of the connector to the cam sensor. The test light did light up and instructions say that its a faulty connection or bad cam sensor. My connection is good. I know that i need to go back to the first test procedure but heres the tricky part. Just for the heck of it i reconnected the old oxygen sensor, left it hanging loose, started the engine and didn`t get an instant code 13 like i did before. How could that be? Could a wrong or faulty new sensor cause this?