tildakoenig1

SM5 boost problem

I'm having issues with my 2010 Renault SM5 (gasoline engine). Mileage is at 143643 km. The check engine light is on, and the engine has reduced power, poor response, and sometimes stalls at idle. Fuel consumption is also higher. I'm also hearing a whistling noise that turns into a loud hissing when accelerating. I suspect a wastegate valve defect is causing a bad boost pressure system. Any similar experiences?

4 comment(s)

That sounds familiar. I've got an SM5, and those symptoms – check engine light, power loss, weird noises – scream boost problems. Have you checked the pressure sensor readings? Turbo lag got progressively worse before I started digging around.

I have not checked the pressure sensor yet. Could you tell me what you discovered during your troubleshooting? Did you also have the whistling/hissing sound?

Yes, the whistling/hissing was definitely there, especially under load. Eventually, the car was almost undriveable. I would suggest going to a workshop to check the wastegate, could be a defect there.

Thanks for the insight. I took it to a workshop, and the wastegate valve was indeed defective, causing boost pressure issues. The repair cost 860€.

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