2009 Dodge Charger Check Engine Light with Coolant Temperature Code and Rapid Coolant Loss

Hi, I'm Nicole and I have a 2009 Dodge Charger. The check engine light came on, and I took it to get an oil change since it was due anyway. The mechanic didn't provide a specific code number but mentioned the issue reads as 'Coolant Temperature Performance.' They also noted my coolant level was about 2-3 quarts low and suggested that if the warning light turned off shortly after, it might just be a low coolant situation. I drove home and the next day, after shopping, I started the car and noticed the check engine light had gone off. I thought everything was fine and assumed the issue was resolved. However, two days later (today), the check engine light came back on. The overflow reservoir is now nearly empty, and I can see coolant boiling — there's a noticeable hissing sound and visible steam coming from the cap area. I noticed that there’s a hose connected to the top of the overflow tank, clamped into a plastic groove. There’s a small puddle of coolant at the dip in the top of the container, and steam is rising from near the cap. The engine does not overheat under normal driving conditions. Given this rapid coolant loss, boiling, and the presence of a puddle, could this be due to a leaking radiator cap? Or is there another underlying issue related to the 'Coolant Temperature Performance' code? I need help understanding what might be causing this and how to fix it. Any insights would be greatly appreciated — especially since I rely on my vehicle daily.