2010 Camaro SS weird cooling issue

When the message popped up saying "Engine Overheating," did it correspond to the temp gauge suddenly working again?

My LS3-powered G8 had an on and off problem where the temp gauge would never budge from cold. Sometimes in stop and go traffic it would suddenly shoot up to the overheating range along with a dash warning, and the fan would suddenly come on. Turned out I had a pinched wire in the harness leading to the temp sensor, probably happened when I swapped the engine. When there was no connection the ECM wouldn't see the high temps, and it would never turn the fan on. Then randomly when the loose wire contacted, the engine would suddenly realize it was overheating. Never a problem on the highway since the fan wasn't required.

If you want to check it, the LS3 temp sensor is located on the driver's side head, toward the front. Possible they damaged the wires when they took the head off. Or maybe it's a bad sensor. Or it's something completely different or a combination of issues.

It's weird that the temp gauge stays dead while the fan is active (and it gives you the message). Maybe the Camaro has multiple temp sensors. I'd look into that. I know there was an ECM change in mid-year 2009. (I had to swap the TB and oil pressure sensor from my original 2008 engine onto my new crate LS3 because the new ones wouldn't communicate with my ECM.) My new motor still only had one temp sensor, but maybe your car has one in the radiator or elsewhere.

The oil pressure showing 0 also makes me suspect sensor or wiring. If that was a real reading, I wouldn't expect the engine to stay running for long.

EDIT: Then again, the car has to be overheating or it wouldn't give you the warning message. You may have multiple issues here.

Boiling noises are of worry, make sure the cap is good?

Make sure all the "air" lines are clear, long story oversimplified, recently a friend replaced a repeatably overheating  tahoe engine only to have the new one do same, turns out one small line on the rad was never punched.

Oh, you have an oil temp gauge? Fancy. I might've been able to avoid my engine swap if the G8 had one of those... or if I were less of a hoon.

The oil temp reading could be sensor or wiring related, but I would also suspect the thermostat at this point.

Does the overflow bottle have a pressurized cap?  It may be bad, too. You may also have a leak somewhere. If get a pressure tester and test the system and the cap.

This would make a whole lot of sense I never knew that before, but clearly must be the issue there.  I've stopped short of buying a new coolant temp sensor (I did get the t-stat) but both advance and autozone near my house have them in stock if I replace the thermostat and it still gives the error.

That hose is clear and working last I saw when I was trying to burp it.  However I will double check it to be sure.  I'm almost thinking maybe theres a blockage somewhere.

Overflow is not pressurized.  So the t-stat comes in saturday so when I work on this sunday I will pressure test as well.  I mean at this point other than that and the sensor the last thing to replace is the water pump, but I've never seen a water pump fail without leaking out the weep hole all over the place as well.

A lot of new pumps are a plastic impeller pressed on a metal shaft. I have seen broken impellers and impellers spinning on the shaft.

Exactly why I was suggesting a T-stat and a water pump. Been there done that on a number of VWs.

it should be fairly simple to plug in obd2 scanner and monitor engine temperature from there.  it will show you the temperature that ecu sees.
to see if water pump is pumping, when cold open the radiator cap and leave it off. start the engine and let it get warm. after that, rev the engine a bit, to like 3k. you should see either some flow in there or the level of coolant move as you do that. DO not go to next step if this does not work.
to see the thermostat, with obd scanner as it comes to temperature. one of the hoses will be cold at start, but as it warms up both hoses will get to be warm at first and then hot. when that happens, check the scanner to see the temperature. should be about 83c. and both hoses should be hot around 87c.

all in all, sounds like water pump is done. Most likely, as mentioned above its plastic POS inside.

Ok so today I replaced the temp sensor, water pump, thermostat, radiator cap, and serpentine belt.  I started the car and was still getting the error, pulled the battery cable, re-attached, no error, everything seems to be functioning fine now.

I don't know what in particular was broken, but now other than the damn head gasket, everything is new!