Oil pressure lamp coming on.
Step 1. Learn how to post year, make, model, submodel, engine size, and possibly engine VIN code, etc. when asking for help. Step 2. Check oil level, if at or below add mark add oil. If light still comes on see next step. Step 3. Replace oil pressure switch (known failure item). If light still comes on again see next step. Step 4. Take car to mechanic to have actual pressure verified/measured and problem fixed(bad oil pump, plugged pickup screen, worn bearings, etc.)