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An H4 fault means you should
1. make sure the outlet your copier is plugged into is grounded. Has a good ground, that is, not just has 3 prongs as seen by visual inspection. There are small devices you can use to test for an open ground in 3 prong outlet, that is sold by hardware stores.
2. reseat the fuser lamp.
3. perform the Fault Reset 14.
4. and if the above does not clear the error, replace the fuser lamp. Which is likely to be what will be needed, at a guess.
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