Crossland X Diesel: Glow Plug Issues & Black Smoke Crisis

Hey there! I had a similar situation with my 2017 Vauxhall Grandland X diesel last winter (I've got some experience working on cars, but I'm no expert). Those symptoms sound really familiar. My car had the exact same issues, black smoke, hard starting, and that annoying glow plug light. Turned out the wiring harness between the glow control unit and the diesel electronics was damaged. Got it fixed at my local Vauxhall specialist for about €155. They had to replace the entire harness, but it sorted all those problems right out. Before you jump to conclusions though, what's your mileage, and have you had any other warning lights? Also, has the engine management light come on at all? This info would help confirm if you're dealing with the same issue I had.

Thanks for your input! Yeah, mine's at 255241 KM and just had a service last month. The engine light hasn't come on yet, but I'll definitely check the wiring harness. Did the repair end up fixing the rough idling issue as well? It's gotten pretty annoying lately, especially during cold starts.

Hey again! Yep, fixing the wiring harness on my Grandland X actually sorted out all those issues, including the rough idling. It's like having a completely different car now! When I had the rough idle, it was particularly bad during the first 5 minutes after a cold start, sounds just like what you're experiencing. The damaged wiring was causing inconsistent signals to the glow plugs, which messed with the whole starting and idling process. Since you mentioned yours has quite high mileage (mine was around 220,000 KM when I had these issues), it might be worth having them check the glow plugs themselves while they're at it. My mechanic said these often wear out around this mileage on Vauxhalls. I ended up getting mine replaced as a preventive measure while they were fixing the harness, cost a bit extra but gave me peace of mind. Just a heads up, after the repair, it took about 3-4 starts for everything to settle back to normal. The ECU needed to readjust to the proper signals. Don't freak out if it's not perfect immediately after the fix! Let me know how it goes with yours. Would be interesting to hear if it's the same issue!

Thanks so much for all the detailed info! That's super helpful, especially the bit about the ECU needing time to readjust, good to know that beforehand so I won't panic! I've just booked it in with my local Vauxhall specialist for next Tuesday. Going to have them check both the wiring harness and the glow plugs, like you suggested. The price seems pretty reasonable too, especially if it sorts out all these issues like it did for yours. Really appreciate you taking the time to share your experience. I'll update you once it's fixed to let you know if it was the same problem. Fingers crossed it's as straightforward as yours was! Thanks again for all your help!