They do not. It's been said on the Internet "don't use soldering guns around guitar pickups", the idea being that if a soldering gun can demagnetize an old CRT monitor, it might also demagnetize a guitar pickup. But I did an test with an old Weller soldering gun with a rather chunky transformer in it. I held the side of the gun to the top of a Strat pickup while it was activated, for about thirty seconds, and found that the pole pieces didn't demagnetize. In practice, the soldering gun would never be this close to the pickups, and it wouldn't be active for that much time. A member named yanyan was asking if it was true that a soldering gun could demagnetize a pickup. Of course, this could only apply to AlNiCo magnets, as ceramic magnets have a much higher coercivity. According this this site https://www.kjmagnetics.com/blog.asp?p=ceramic-remagnetization , it took a field of eight to ten thousand Gauss to magnetize a ceramic magnet, so it would take a similar strength to degauss it as well, which is achievable in between two neodymium magnets that are almost touching together. But even with AlNiCo and it's lower coercivity, a soldering gun doesn't produce a strong enough magnetic force to degauss the magnet. Even though the Gaussmeter shows precision in the 10's, the number bounces around a lot in real time, so the accuracy is more realistically about 5 milliteslas, but that being the case, the magnets appear to have lost no residual flux, even with the soldering gun directly over it, operating for about a total of 30 seconds. I hooked up a Fender Custom 54 neck pickup to an oscilloscope, and measured the voltage of the pickup at difference distances: The voltage output with the coil directly beside the pickup was 16 volts, which is about sixty times greater than the typical output of a Strat pickup.