Oil pressure guage needle on wrong side of low-end pin
While driving, I noticed my oil pressure guage showing 0, but the check engine light was not lit. To be on safe side, I stopped and checked oil level and it was fine. When I started up, I noticed that the guage was at about the 5 O'clock position (well below 0) when off, and when engine started, it went _up_ to the low-end pin. So it looks like the meter needle somehow got on the wrong side of the pin. What's the appropriate fix for this?
The truck is a 2001 Mazda B3000 with manual 5-speed, extended cab "Dual Sport" with 166KMiles.