Strange but true
Yes, be SURE to search this site. There is an engine wire harness that includes most of the upper engine accessories and engine management connections. Is the car in warranty? It's a warranty repair. If the car is out of warranty, how friendly is your friend with his dealer's service department? There may be a chance for a goodwill replacement. I managed a 50% goodwill replacement on my '92 500E with 109K miles. But I spent more than a few thousand in service at my local dealer over the past year. When the old harness came out, the insulation was cracked throughout, like every half inch. It was a mess. Good luck!
1995 E320 Wagon Moonstone Grey/Parchment 106K mi.
2007 E63 AMG Graphite/designo 75K mi