Whenever I started my 2001 Explorer Sport the oil pressure gauge sat at zero (which is quite scary) until a few minutes later when the gauge jumps up to a normal reading. Since there was no pinging and my Explorer hadn't exploded I decided it was probably the oil pressure sensor. Go to FORD to fix it? F-that. Fix it yourself for $15 and 20 mins of your time: Start by taking the drivers side tire off and peeling back the small upper bit of the rubber wheelwell Look in from the wheel well. This is the culprit with the single white/green wire comming out of it. Start by unplugging the connector. Unplug that sucker and unscrew it using a deep socket. Old and new. Screw it in using your hand first, then tighten with a wrench. Put everything back in reverse order (plug it back in, replace the wheel well, put on your tire, etc.) The gauge pops right up every time you start it up. Problem fixed.