Astra Diesel Troubles: Black Smoke and Power Loss Mystery

Hey there! I had a similar issue with my 2016 Vauxhall Insignia diesel (I'd say I have some experience with these cars). Those symptoms sound very familiar, my car was doing exactly the same thing last summer. Turned out the wiring harness to the boost pressure actuator was damaged on mine. Got it fixed at my local Vauxhall specialist for about €155. They had to replace the entire harness, but it sorted all those issues, no more black smoke, jerking, or weird noises. Could you share your Astra's mileage and service history? Also, are you getting any specific error codes? This info would help confirm if it's the same issue I had. Quick tip: don't wait too long to get it checked, driving with boost pressure issues can lead to bigger problems!

Thanks for your detailed reply! My Astra's at 194182 KM and had its last service just 3 months ago. Haven't had a chance to get the error codes read yet, but planning to do that tomorrow. The symptoms you described with your Insignia are spot on, especially that whistling noise that's driving me crazy! I'll definitely check out the wiring harness suggestion. €155 sounds way better than what I was worried it might cost. Is your mechanic anywhere near Manchester by any chance?

Hey again! Yeah, I remember going through the exact same headache with my Insignia, that whistling noise really gets to you, doesn't it? Unfortunately, my mechanic's in Leeds, bit far from Manchester. But I can recommend checking out Auto-Tech on Chester Road in Manchester, heard good things about them from other Vauxhall owners. Just a heads up, with your mileage being similar to what mine was (mine was around 180000 KM when it happened), it's pretty likely we're dealing with the same issue. Once you get those error codes, it'll be easier to be sure. Mine showed P0299 and P0234, which pointed straight to the boost pressure problem. After getting mine fixed, it's been running like a dream, no more black smoke, weird noises, or that annoying jerking. Just make sure whoever looks at it checks the entire wiring harness thoroughly, sometimes they just try to patch it up, but in my experience, a full replacement is worth it. Let me know what those error codes show up as, I'm curious to see if it's the same problem. Good luck with it!

Thanks so much for all the detailed info and the garage recommendation! I'll definitely check out Auto-Tech. Just got back from getting the codes read and, would you believe it, got the exact same codes, P0299 and P0234! That pretty much confirms what you were saying about the wiring harness. Really appreciate you sharing your experience, it's saved me a lot of worry and probably some money too. I've booked it in for next Tuesday, so hopefully I'll be back to normal driving soon without that awful whistling driving me up the wall! Thanks again for all your help! Really glad I asked here first before panicking and taking it to the main dealer.