So I think I am having the same issue, but I am a little unsure and looking for some confirmation. My 2005 Xterra oil pressure gauge pegged at H, but after it warms up, it starts coming back down, but nowhere near where it should be. Could the issue still be the sending unit? Is there a way to test this? Or other symptoms I could look for if the pressure was really too high? I checked the oil level, it is fine. I changed the oil and oil filter about 1 month ago. Drove it yesterday with no issues that I could notice. Thanks!