Is it a sensor or a code needing cleared?

The fan on my car stopped abruptly while I was stuck in traffic, causing my car to overheat which then caused it to need a new head. I took the head to a machine shop had it redone. Finally got it back after five months. It looked great. All new valves seals the gasket. Everything has been perfect. I have gotten everything put back into my car. Done a new oil change and tuneup. Found out the issue with the fan was not even my fan. It was the fuse box itself so I’ve had to replace that then the car just wouldn’t start. Found issues with the starter so replaced that and now that it is finally running it is throwing a code for oil pressure sensor and I am trying to figure out if it’s still reading codes when my car went down that were never cleared or cleared properly or if it is in fact, a faulty sensor. Everything looks great all of my oil coolant. Everything is where it should be but now it is in limp mode and I just need help.