It's not fun at all. Ive changed them on 2 different motors. I was rebuilding them in the first place because I bought the trucks with bad engines. 1 motor had been apart before I owned it and all 6 tips broke off when I removed them. The other one was a complete nightmare. Broke off the heads on all 6 ended up drilling out the glow plugs. I'm sure mine were worse case scenarios, but there is no easy way. Might get lucky with lots of wax and a ton of patience
Try this first: Wiggle the connoctor on the the glow plug, even pull it off and reinstall. I have had a couple different glow plugs pop this code, I did this and they went away. In my experience with my truck, many codes that pop up are more about a loose or tarnished connection or an ECU boot up glitch, than the actual problem indicated. If the issue doesn't go away and you have to change the glow plug, there are a few videos on YT that give different types of penetrating fluids to help loosen things up so as not to break it.