I found a small oil leak at my oil sending unit. I pulled the cover off and removed the wire connected to it to check for the leak. Before this my oil pressure guage always read dead on the 3/4 mark. After I reconnected the wire (without changing the sending unit or anything) the reading pegged the top of the guage. I then went and got a new sending unit and replaced the old one. It still reads as high as it will go.

Can anyone tell me what is going on? If this is bad? I just don't understand how removing the wire and putting it back on could make it read so much higher?Thank you.