Mark X Belt Tensioner Issue

I had something similar happen on my Mark X. Is it making a squealing noise, especially when the engine is cold? It could be a bad belt tensioner pulley causing the serpentine belt to slip.

Yeah, it's squealing pretty bad, especially when I first start it up. How did you figure out it was the tensioner? Was the belt drive affected?

The squealing was the big clue. My mechanic checked the belt tension and saw the tensioner pulley was wobbly. Best to get it checked at a workshop, they will know. I needed a new tensioner. The whole belt drive will suffer in the long run if you don't fix it.

Thanks for the advice! I took it to my mechanic, and you were right, it was the belt tensioner. Cost me 455€ to get it sorted. Engine performance is back to normal now.