In my VW Passat (generation B8, TDI 2.0 190HP diesel engine) I had to replace first cylinder 1 and then somewhat later cylinder 4 glowplugs within the firtst 5 years I had the car. I used OBD Eleven to scan the car for errors. With glowplugs you never know when they will fail and why that then is. I had a previous Opel Vectra diesel for 13 years and 380.000 km and never had to replace the glowplugs and in my brand new Passat 1 glow plug failed after 3 years and the other after 4 years. And yes, it is possible to start and drive on with one, even two, defective glowplugs, but that's another story entirely. I decided to do it myself and bought a pair of special pliers, copper grease, some round cleaningbrushes, a box of these 4 cheap glow plugs and two special bits in M10 and M12 size to fit over the glowplugs to unscrew them with a variable low torque wrench. Compared to what a garage would have charged me this was very cheap. The downside personally was that I am notoriously slow with doing chores in and around the house and this task was no different. So it took me a while to do it, but, after using loads of WD40 on a warm engine to loosen up the existing glow plugs I needed to replace I succeeded in replacing the old Bosch glow plugs with 2 of these no name glow plugs and everything was fine again afterwards.I deliberately did not replace the still functional glow plugs of which one is an expensive type of special glowplug that also has a pressure sensor built in it. No point in throwing away money for something which may not break at all. I know some people would replace the whole set, but I think that's premature, expensive and wasteful. Only replace something when it is broken, at least when you can do it yourself and this is not that difficult to do. There are many good videos on youtube to watch. I replaced them with a still warm engine and after days of WD40 lubrication to loosen them. Maybe that wasn't all necessary, but it certainly can't hurt and may prevent a broken glowplug when it won't get out easily. You really need to watch a video, but don't use too much copper or lithium grease, just use your finger to spread it out thinly and into the screwwindings. You don't want to electrically isolate the whole thing either !Why did I give 4 stars and not 5 ? Well, it seems 1 of the 4 glowplugs was defective/DOA so I had only 3 functional ones. This may have been a one off/fluke and in my case it was't a problem as I only need 3 of this type of glowplug in my engine as the 4th one is a special type, you know, with pressure sensor built in and such, so I would never have needed 4 and now I still have 1 good one as a spare. But it should not have happened, you pay for 4 not 3, so that's why I gave one star less.