Hello and welcome to 2CarPros. The first thing I'd ask is has anyone actually checked the oil? Unless you've checked it yourself, or witnessed them checking it, do that first. Then I'd make absolutely sure that they replaced the "oil level sensor" and not the "oil pressure sensor." Yes, mechanics/shops do make that mistake all the time as they don't realize that some cars have both sensors/switches.
Otherwise, what has probably happened is that one of the wires going to the sensor has short circuited or broken off somewhere in the system, causing the computer to think that the oil level is low and turn on the warning. What you'll need to do is take the connector off of the sensor and check for continuity using a multi-meter or ohmmeter. Either one is available at all of the parts stores, Sears, Lowe's, Home Depot, Walmart, Amazon, Ebay, and so on, for less than $20.00. You'll unhook the connector, then connect one of your meters leads to the ground connector, and the other to the engine block or the negative battery terminal (preferred, if doable). You should get a reading of 0 resistance, meaning that there is no problem there. Wiggle and jiggle the connector around while it's connected to see if that causes the reading to jump to infinity (meaning that there's no connection). If it jumps like that, then you have to replace the connector and/or the wire. Now check continuity between the negative/ground connector and the positive battery terminal. Should be infinite resistance, unless there is a problem with the wiring. Run the same test with the positive lead connector. However, it should show infinite resistance between it and the negative cable, and 0 resistance between it and the positive battery cable. Again, wiggle and jiggle.
Here's the multi-meter that I have. It has served me well for almost ten years now: https://www.amazon.com/gp/offer-listing/B000X5TSUA
Check into all of that, and let us know what you find by replying to this thread. We'd love to know what the issue is. Of course if you have more questions, I'll be glad to continue helping you.
Images (Click to enlarge)
Sunday, February 24th, 2019 AT 5:09 AM