Incurrable malfunction indictor and engine oil light

I have a 2006 Dodge magnum. About a year ago the engine malfunction indicator and engine oil light came on. The OBD said it was a faulty oil sending unit, which has since been replaced twice including a new pigtail. Local Dodge service offered to further diagnosis work for $500 but this would not include any repairs. Both lights come on when I first start the car. In about 5 minutes the engine oil light goes off. Sometimes the malfunction indicator light goes off. Any thoughts? I am using Dodge's recommended 5W-20 API certified oil.