Bought a 2007 Audi A4 quattro sedan and the old owner grounded the MAF sensor and did it poorly, how do I fix this???

 

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Normally the MAF is grounded via the connector with wire going to a grounding point somewhere in the harness. I'm not sure which wire it is but you can splice into it and run your own to anywhere close by where a bolt goes into the body shell. This should be a straight forward fix.