The 1.9 uses its own unique glow plugs. They are self regulating "duraterm" type plugs. Bosch, Beru and Lucas/Delphi all make a version of this plug. They stay on for 3 minutes after a cold start so regular fast or slow glow plugs will burn out quickly. They can be identified by the reduced diameter, tapered tip
i can't say for sure that it's 100% accurate, but so far, this method hasn't proven inaccurate for me yet. I remove the power bus from the plugs, connect my test light's clip to the positive terminal and then touch the ends of the installed glowplugs. burnt out plugs don't light up the tester. verify after removal by powering them on the bench.
Do mk2 glowplug rules apply to my 93 td aaz???