Land Rover Diesel Smoke & Glow Plug Warning Signs

I had nearly identical issues with my 2011 Land Rover Discovery diesel at 175K km. The symptoms were exactly like yours, black smoke, cold starts, and that annoying glow plug light. My mechanic found the wiring harness between the glow control unit and ECU was damaged. Some wires were corroded and had poor contact. Initially, they suspected just glow plugs, but the diagnostic showed the harness damage was preventing proper communication between the control units. This was causing incomplete pre-heating cycles and messing with the DPF regeneration. The fix wasn't quick, they had to replace the entire wiring harness assembly. It was a serious repair since they needed to access some tricky spots in the engine bay. The car's been running perfectly for the past 18 months since the repair, no more smoke, starts fine in cold weather, and DPF works normally. If your symptoms match mine, I'd recommend getting the wiring checked before jumping to glow plug replacement. It's worth having a proper diagnostic done by a Land Rover specialist who knows these specific issues.

Thanks for sharing your experience! Sounds exactly like what I'm going through with my Freelander. Really helpful to know about the wiring harness issue, wouldn't have thought to check that. Been worried it might be something more serious with the engine itself. Would you mind telling me roughly how much you ended up paying for the whole repair? Also curious if you've had any other electrical gremlins pop up since then? Trying to get an idea of what I might be in for!

Hey there! Happy to give you an update on my Discovery repair costs. The final bill came to 395.00 € to fix that faulty wiring harness between the glow control unit and engine control unit. Worth every penny though, the car's been running like a dream since then! I've had zero electrical issues pop up in the past year and a half. The black smoke is gone, cold starts are smooth as butter now, and everything's working exactly as it should. Turns out it was definitely a malfunctioning glow plug caused by that damaged wiring harness, once they sorted that out, all the symptoms disappeared. My advice? Get it checked out sooner rather than later. These electrical gremlins can be tricky, but catching them early usually means a simpler fix. Plus, driving around with those symptoms isn't great for your engine in the long run. Trust me, I know the pain of dealing with these issues, but once it's fixed properly, you'll be amazed at the difference. My Discovery feels like a completely different car now!

Thanks so much for the detailed info! I bit the bullet and took my Freelander to a new mechanic yesterday. You were spot on, it turned out to be a similar wiring issue. The diagnostic showed some corroded wires near the glow plug control unit. Got it all fixed up, and the difference is incredible! The repair was a bit pricey at 450€, but honestly, seeing how well the car runs now, it was totally worth it. No more black smoke, starts up perfectly even when cold, and that annoying check engine light is finally off. The mechanic was great too, really took the time to explain everything and show me the damaged parts. Can't thank you enough for sharing your experience. You saved me from potentially replacing parts that weren't actually the problem. The car's running better than it has in months! Definitely keeping this mechanic's number for future repairs.