Seat Cordoba belt tensioner issue

The belt-handover failure suggests a more serious problem than just belt squeal. I once faced a similar issue with my Opel Vectra; a defective tensioner pulley caused timing belt slippage. I would check the timing belt. Are you experiencing any loss in engine performance?

Timing belt slippage? I am not sure about that. How did you diagnose it initially?

Indeed. The initial symptom was belt squeal, which quickly degraded into erratic engine performance. A thorough inspection revealed that the tensioner pulley had failed, causing the timing belt to lose tension and slip. Consequently, the engine timing was off. Considering the symptoms you have described, I recommend having a qualified mechanic inspect the belt drive and tensioner pulley. Do not delay the inspection; a broken timing belt can cause catastrophic engine damage.

Thanks for the input. Turns out the tensioner pulley was indeed completely shot. Got it replaced for 455€. Engine performance is back to normal, and no more belt squeal.