So my truck has been sitting for a while, due to driving a company truck and being out of town. I try to fire it up and drive it for a few hours a weekend when I am home.

First big trip out since sitting (~400miles), the oil pressure sensor drops to 0 in the middle of nowhere and it's 20 degrees outside at midnight. Finally limped it in to a town, traced it down to be the oil pressure sending unit- put a new one in- not a problem since.

Just tonight coming home from dinner, pull in to the driveway and was idling for a moment to let it cool down. Tachometer drops to 0 and the check engine light comes on. No real changes in the idle, or other signs of engine changes. Shut it off, fired it back up and the tach worked again. Engine light still on, I checked it for codes and nothing popped- now the Check Engine Light is off, and no other problems. Anyone have any ideas?

Thanks in advance for any help.

Nick.