Originally Posted by Spenzer4Hire

This afternoon I parked my car and went into a store for about 10 minutes. When I got back i heard the whirring sound of a shop vac coming from under my hood. I drove a couple of miles back to work and it was still running even when the engine was turned off. I located the part (air pump) but didn't know what it was. I quickly ran out to a local repair shop where they pulled the plug on it. It was crazy hot and smelled a little like burning, but it still appears to function. No CEL or anything abnormal.

After we plugged it back in and I started the car it's been functioning properly (i.e. shutting off when the car is off). Thoughts? If it's a failing relay, should I have it proactively replaced? I'm currently unplugging the air pump when I'm not driving, just in case it decides to start up and I'm not around to hear it.