Volvo V40 Diesel Check Engine Light Power Loss

My 2012 Volvo V40 diesel has a concerning issue at only 31299 km. The check engine light is on, with reduced engine power, poor engine response, and increased fuel consumption. I suspect a boost pressure problem and checked for leaks, but found nothing. Could this be a faulty boost pressure sensor, or something with the turbocharger?

4 comment(s)

That sounds frustrating! I had a similar experience with my Renault Megane. Check engine light, power loss, and awful lag. Have you checked the vacuum switching valve? That was the culprit for me, it controlled the boost pressure.

Thanks for the quick reply! Is the vacuum switching valve difficult to access and test? I'm reasonably handy, but I don't have professional diagnostic tools. Any tips on identifying if that's the source before I start?

Honestly, on the Megane, it was a pain to get to without lifting the car. Given the symptoms and low mileage, it's quite likely. If you lack the tools for proper diagnosis, it's probably best to get it to a workshop, so you do not cause further damage. They should be able to confirm it quickly and give you a quote. Sorry I can't be more specific without seeing the engine layout.

Took your advice and went to the workshop. You nailed it – defective vacuum switching valve. Repair cost was 140€. Massive thanks for pointing me in the right direction! Engine performance is fully restored.

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