Corsa Diesel: Black Smoke & Glow Plug Mystery

Hey there! I had a similar issue with my 2005 Vauxhall Astra diesel (got some experience working on these cars). Those symptoms sound really familiar! Had the same drama with the pre-glow light and black smoke. Turned out the wiring harness between the glow control unit and ECU was damaged. Took it to my regular workshop, and they diagnosed it pretty quickly. Cost me around 395€ to fix, mainly for the new wiring harness and labor. Since then, no more starting issues or black smoke. Which engine variant does your Corsa have? Also, have you had any other warning lights or symptoms? Might help narrow things down further. Pro tip: Don't wait too long on this one, could cause more expensive problems if left unchecked.

Thanks! Mine's at 172002 KM now and had its last service about 2 months ago. The mechanic didn't spot any issues then, which is why this is so frustrating. I'm thinking it might be worth getting it scanned first before jumping to conclusions. I've heard these symptoms could also point to a faulty MAF sensor or fuel injectors. Did your mechanic run any specific diagnostic tests before finding the wiring issue? Thanks for the heads up about getting it sorted quickly, definitely don't want to end up with a bigger headache!

Hey again! Yeah, with my Astra they actually ran a full diagnostic scan first, that's always the smart move! The scanner showed multiple fault codes related to the glow plug system, but what really pointed them to the wiring was the erratic voltage readings they got when testing the glow plug circuit. You're spot on about the MAF and injectors though, had those replaced about 50k km ago on my car (they were acting up too). But the symptoms were a bit different then, more like rough idling and poor acceleration, not so much the black smoke and glow light issues we're talking about now. Since you mentioned your recent service, maybe check your service records? My wiring issue started showing up gradually after a timing belt change, think they might've accidentally nicked the harness during that job. Just something to consider. At 172k km, these things can pop up. My Astra's at 198k now and still running strong after fixing that wiring mess. But yeah, definitely get that scan done first, saved me from replacing parts I didn't need to! Let me know what the scan shows, curious to hear if it's the same gremlin I dealt with!

Thanks so much for all the detailed info! You've really helped put my mind at ease. I've just booked it in for a diagnostic scan tomorrow morning, better safe than sorry, right? Now that you mention it, they did do some work near the timing belt area during the last service, so I'll definitely bring up the possibility of damaged wiring to the mechanic. Really hoping it's something as straightforward as what you experienced with your Astra. Will update the thread once I know what's what, might help someone else down the line with similar issues. Thanks again for taking the time to share your experience!