An Etymological Dictionary of the German Language/Annotated/Funke
Funke, masculine, from the equivalent Middle High German (not a classical form) vunke, masculine, Old High German funcho, masculine, ‘spark’; compare Dutch vonk, ‘spark,’ Middle Low German and Middle English funke, ‘small fire, spark,’ English funk, ‘round wood, steam, stink.’ Classical Middle High German has vanke, masculine. It is uncertain whether Gothic fôn (genitive fŭnins), ‘fire,’ is allied; it is more probable that Sanscrit pâjas, ‘splendour, gleam of light,’ is primitively cognate.