Peugeot 208 Gasoline Wastegate Issue

I drive a Peugeot 208 Gasoline as well. Your description sounds awfully familiar. Check engine light, reduced power, whistling... it's all pointing to the turbo. When was the last time you inspected your intercooler hoses? Any sign of oil leaks around the turbocharger itself? It could be a split hose or a failing wastegate actuator. But stalling at idle is a bit worrying, are you sure that the whistling is coming from the turbo area?

The intercooler hoses appear to be in good condition, with no visible cracks or leaks. As for oil leaks around the turbocharger, I haven't noticed anything obvious, but I'll take a closer look. I'm unsure about the source of the whistling, it's difficult to pinpoint the exact location. Could it be the wastegate, even if the intercooler hoses appear fine? And could a faulty wastegate really cause the stalling at idle?

A faulty wastegate could definitely contribute to the whistling and loss of power. The ECU will try to compensate for the loss of boost, but only to a certain degree. And yes, in extreme cases, it could even cause stalling. I had a similar thing happen with my 208 Gasoline, it was indeed the wastegate. Considering all the symptoms you are describing, I'd say you should take it to a workshop to have the turbo and wastegate properly inspected. It's not worth risking further damage.

I followed your suggestion and took my Peugeot to the workshop. After a thorough inspection, they confirmed the defect in the wastegate valve. The final repair cost came to 860€. I appreciate you sharing your experience; it saved me a lot of unnecessary troubleshooting!