2019 Hyundai i40: Black Smoke, Check Engine Light, and Erratic Behavior

Hey there, just read your post and it reminded me of a similar situation with my 2016 Hyundai Sonata. The symptoms were almost identical: black smoke, check engine light on, the engine cutting off randomly, and a hell of a fuel consumption. My ride felt like a runaway roller coaster when I tried to accelerate and stalled during idle. Smell from the exhaust? Worse than week old leftovers. I took it to my go-to garage and the diagnosis was a defective wiring harness/plug. Apparently, this was causing all sorts of miscommunication between the car components. It wasn't an easy diagnosis but props to the technicians for their keen eye. Anyway, to fix it, the whole wiring harness had to be replaced as some parts were beyond repair. The fix was not immediate, needed several hours, but it tackled every single problem you mentioned and mine too. Of course, hand-in-glove, it solved the problem and the ride's been smoother than ever. Yes, it was a serious issue since it was messing with my car's functionality. My advice? Don't stall it. If your problem is the same, it'll just get worse the longer you wait. Good luck!

Hey, your story really resonates with me. This sounds exactly like what's going on with my i40. It's a pain in the rear, but knowing that someone out there has dealt with the same issue helps, really. So you ended up replacing the whole wiring harness, huh? Do you remember how much that set you back? Just trying to get a sense of what I might have to shell out. Also, has anything else popped up since you got it sorted or has it been plain sailing? Any extra info would be bloody helpful, cheers.

Hey. I can feel your concern, was in the same boat not too long ago. For the dough bit, replacing the harness did dig into my pocket a bit. Cost me 95.00 € to be precise. But trust me, it's been worth every penny. Ever since those fellas at the garage got their hands on it, every problem vanished. No more black smoke, roller coaster rides, or that dreadful smell. About the fuel level sensor, you nailed it! There was indeed a malfunction which got sorted when I took it to the mechanic. So since then, it's been nothing but plain sailing, just the way we like it. I recommend getting it checked ASAP, before it causes more issues than already. All the best!

Wow, that's some priceless insight right there. Can't thank you enough. 95.00 €, huh? It does sound a little steep, but if it means getting rid of all the issues, then I'd say it's money well spent. Now that I think about it, I've been spending a fortune just trying to keep the fuel tank full, so maybe this will even save me a bit in the long run, eh? Okay then, that settles it. First thing in the morning, I'll fire up the car, hold my breath with the stink, and get her straight to the mechanic to check for a faulty wiring harness. If it ends up as smooth sailing after that, well, that'd be worth every penny. Appreciate your advice. Here's hoping my story ends up like yours, just a and his smooth-running machine. Cheers!