Astra Diesel: Black Smoke & Power Loss Mystery Solved?

Hey there! I had a somewhat similar issue with my 2011 Vauxhall Insignia diesel. The symptoms you're describing sound very familiar, my car was doing almost the same thing last year. Turned out it was an electrical bypass valve problem on my turbo. Got it fixed at my local Vauxhall specialist for about 250€. They had to replace the valve and recalibrate the system. Before I share more details though, can you tell me your engine size and mileage? Also, have you scanned for error codes? This would help confirm if we're dealing with the same issue. If it's what I think it is, don't drive it too much until it's fixed, could save you from bigger problems down the road.

Hi, thanks for the reply! My Astra has 21206 KM on the clock and just had its service last month. Haven't scanned for codes yet, but planning to get that done tomorrow. Was your car also making that distinct whistling noise before you got it fixed? The symptoms you're describing sound spot on with what I'm experiencing. I've been trying to minimize driving it since these issues started.

Hey again! Yeah, my Insignia had that exact same whistling noise, it was actually one of the main things that got me worried. It was particularly noticeable during acceleration, right? Kind of sounds like a loud kettle when you're trying to speed up? After getting my bypass valve fixed, that annoying whistle completely disappeared. Mine started showing these symptoms around 180,000 km, so you're quite lucky catching it early at 21,206 km. That's actually really low mileage for these issues, which makes me wonder if there might be something else going on too. When I took mine in, they discovered that the electrical connection to the bypass valve was corroded, causing it to stick partially open. That's what was causing all those symptoms, the black smoke, power loss, everything. The whistling was basically boost pressure escaping where it shouldn't. Definitely get those codes read, that'll confirm if it's the same issue. My error codes were related to boost pressure control, which helped pinpoint the problem. Let me know what codes you get, I'm curious to see if they match up with what I had. Just a heads up, while my fix was around 250€, prices might have changed since last year. But at least it's not usually one of those wallet-crushing repairs!

Thanks so much for all the details! Yeah, that whistling sound is exactly what I'm hearing, especially when accelerating. It's good to know it might not be as expensive as I feared. I was worried it might be something major with the turbo itself. I'll definitely get those codes read tomorrow and let you know what comes up. Given what you've described, it does sound like it could be the same issue, although you're right, it is pretty early for these problems considering my low mileage. Maybe I should mention that to the mechanic too. Really appreciate your help! I'll be keeping my fingers crossed that it's just the bypass valve. Will minimize driving until I get it checked out. Thanks again for sharing your experience, it's been super helpful!