I got 4 MB sensors from FCP Euro and new bolts for good measure (purely cosmetic). I also got 4 cam position sensor sacrificial harnesses to make it harder for oil to wick up to the ECU. I did check my ECU plugs and they seemed totally dry. I douched both the ECU female side plugs and also the cam position sensor plugs with electrical contact cleaner and gave everything a blast of air. There was nothing wrong with my old cam position sensors other than leaking some oil into the plugs (all were wet). I checked all 4 magnets before I bought the car and those plugs were all dry.
ECU plugs
ECU just pops out of its place once the top engine cover is removed (also just pops out). Right around this time it occurred to me that I may have just reset the OBD readiness and I had an inspection appointment in an hour!! Smooth move. More on this later.
Cam position sensor replacement & sacrificial harnesses from ZZP (a common GM performance vendor).
Final product. Can't see the line, can you Russ?
I started the engine and of course everything seems fine. But I wasn't too worried about that part. I plugged in my generic OBD-II reader and.....all monitors still ready! I think this is a thing on modern ECUs. Don't know if there is an internal battery or if it is just an NVRAM thing. Either way, should be good to go. In the future, I will periodically check the sacrificial harnesses and in theory, replace them and the cam position sensors (utilizing the FCP Euro lifetime warranty) as often as I need to.
Oh, I guess I should mention that this issue is scary because not only can it trash the ECU eventually, but I have read multiple reports that before the ECU quits working entirely, it can grenade the engine because it has, say, incorrect ignition timing (or even fuel timing) due to I would assume scrambled cam position signals. Or the oil just FUBARs the ECU and it just goes nuts. Either way, this is solid PM to do. Obviously the dealer fix is a new engine harness which costs insane money (a 5 figure job I believe). No need to do that though.