Black Smoke & Power Loss: Defender Diesel Diagnosis Help

Hey there! I had similar issues with my 2012 Land Rover Discovery diesel last year. Black smoke and poor performance were exactly my symptoms. Turned out it wasn't the Lambda sensor in my case, it was actually a cracked exhaust manifold and a faulty EGR valve. The mechanic spotted the exhaust leak during inspection and showed me the crack. The manifold was allowing unmetered air into the system, messing with the engine readings and causing the ECU to dump extra fuel. That's what caused the black smoke and rough running. It was a pretty serious job that took two days to fix properly. They had to replace the manifold gaskets and clean the EGR system too. Since the repair, my Discovery's been running smooth with no smoke or performance issues. Your symptoms sound very similar, so might be worth getting the exhaust system checked thoroughly, especially around the manifold area. A proper diagnostic scan would also help pinpoint if it's EGR related. Best of luck!

Hey again! Thanks for sharing your experience. The manifold and EGR valve issue sounds exactly like what I'm dealing with. Would you mind telling me roughly how much you ended up paying for the whole repair? Also curious if you've had any other issues pop up since getting it fixed? Really hope I can get this sorted without breaking the bank. Those Defender repairs can get pretty expensive! Cheers

Hey there! Quick update on my Discovery situation, actually turned out I was wrong about the Lambda sensor in my initial reply. Just got back from the mechanic yesterday and it was indeed just an exhaust leak that needed fixing. Cost me 265€ in total, which wasn't too bad considering I was worried it might be something more serious! Since the repair, my Discovery's been running like a dream, no more black smoke or performance issues. Haven't had any other problems pop up either, which is always a relief with these vehicles! The mechanic did a thorough job, and while they were at it, they checked the Lambda sensor too, funny enough, that was actually faulty as well but got sorted as part of the fix. Sometimes these issues are connected, you know? Trust me, I know the feeling about repair costs, I was sweating bullets before I got the quote! But this turned out to be pretty reasonable in the end. Hope you get similar good news with your Defender! Let me know how it goes!

Hey! Just got back from the mechanic today, what a relief! Took your advice and had them do a full inspection. Turns out it was definitely the exhaust leak, just like you mentioned. The mechanic found a crack in the manifold and some gunk buildup in the EGR valve. Fixed everything for around 300€, not cheap, but way better than I was expecting! They sorted out both issues and did a full system clean while they were at it. The Defender's running like new now, no more black smoke, and the engine's smooth as butter. Took it for a proper test drive, and what a difference! Power's back to normal, and it's not drinking fuel like before. The check engine light's gone too, which is a bonus. Really appreciate you sharing your experience, helped me avoid getting ripped off and going down the wrong path with the Lambda sensor first. Sometimes it really helps to hear from someone who's been through it! Thanks again for all your help!