I actually lost the one at the rear of the engine at the begining of a drive. However, the reason I turned around at the end of my gravel driveway was because I had a brake issue and decided it needed to be addressed. When I turned around in the road and headed back up the drive I saw the trail of coolant that went all the way back to where I fired it up. I had some spares, tapped (pounded) it in with some difficulty due to the angle, put whatever epoxy goo I had on hand over the top and no problems since. The next day, quite by accident I spied the errant plug in the grass, right where I had started the engine. Bonus!