I changed the oil in my truck last week, and began to panic when I started it up, checked the oil pressure gauge, and saw it pegged at 120PSI (the highest the gauge goes). I immediately shut it down, configured a PID on my Insight CTS2 monitor for oil pressure PSI, and started it back up – to find it reading 0PSI through the ECU. Again, I shut it down to prevent damage, but at this point suspected a bad sending unit. I checked the oil filter and it had oil in it, telling me oil was flowing, and the that accompanied with the fact that there weren’t any weird sounds gave me a little peace of mind. I unplugged the sending unit and the gauge, which was pegged at 120PSI dropped to 0PSI, so I ordered a new one.
Repacing the sending unit corrected the issue. It’s really odd that it happened to fail when I changed the oil. It is out of the way of anything I was doing and shouldn’t have been touched, and I check my gauges constantly so it wasn’t broken for long. Maybe just a scary coincidence.