Cat C15 oil pressure issue

I drove a 2007 379 with a C15 ACERT, it had a 625 until it scattered around 898k. A brand new 550 was installed about 13k ago. Today when I left my house I noticed my oil pressure was around 40 psi after a 20 minute warm up, as opposed to the normal 60-65. As the oil warmed up it dropped to about 25. I pulled over and let it idle, then it dropped down to 10. Oil is full, oil temp is normal, no knocking or pinging is occurring. I drove it to my load point a few miles away and shut it down again, then turned the key on to self test the gauges. With the key on, engine off, the gauge will jump up to 75 psi, then when I start it, it will drop back down to 10. Faulty sensor?

 

It did this once before but fixed itself after a few minutes. Taking it to a shop to have it checked out

 

It was a bad sensor. My A/C stopped working as well on my way to the shop so I pulled over and found the belt was gone, shredded all through the engine bay. What a day

 

Thank you, everybody for your input