Q: Oil pressure light comes on in the morning when the car is cold, but goes off if I turn the car off then back on.

Hello, thank you for writing in. The sensor, or oil pressure switch, can be tested. If the sensor appears to be within the factory spec, the first thing to check is if you have the right viscosity oil. If the wrong oil, particularly higher viscosity, is put in, the oil pump will not, at least initially, generate pressure as intended. If this issue just started after the oil was changed, of course that itself suggests the foregoing possibility (wrong oil). Assuming the oil is not the issue, and the sensor or switch is OK, it is easy to verify the oil pressure using an external test gauge and of course the pressure should be verified because if there is inadequate oil pressure such will will prematurely wear out the engine bearings. Here at YourMechanic, we can have a technician come to your home or office to inspect and diagnose this issue for you, and make or suggest the necessary repairs.