2018 Volvo V40 Diesel Issues: Black Smoke, Struggling Start, and Erratic DPF Regeneration

Hey there, Sounds like you're dealing with the same headache I had with my 2015 Volvo V60 not too long ago. Had the same symptoms: difficult start-ups, that annoying glow light that just wouldn't go off, and loads of black smoke every time I hit the gas. Turns out, my suspicions were right. The Wiring harness from the glow control unit to the digital diesel electronics was in a rough state. They identified it as defective/damaged and the culprit behind most of my woes. Now, this ain't a light issue. Your vehicle's electronic system is crucial for it to operate effectively. In my case, the mechanic had to replace the whole harness. It was a pretty in-depth job because the wiring harness is interconnected with multiple components in the engine's system. Once it was taken care of, the car's performance improved significantly - no more choking on start-ups or excessive black smoke. Remember to get it checked at a reliable workshop ASAP. If left unchecked, it can develop into something much more disastrous for your engine. And yes, find a good mechanic, not all of them out there are nightmares. Good luck!

(Translated from German)

Hey, I'm stuck with the same sort of trouble with my V40 as well. Going through your message felt like déjà vu! Black smoke, the pre-glow light... you name it. It's a bit of a nightmare, to be honest. Sounds like the issue with the wiring harness was a bit of a job for your mechanic. Do you recall how much damage it did to your wallet? Did replacing the harness sort the problem completely or have you had any additional problems along the way? Fingers crossed this can get sorted sooner rather than later! Cheers!

(Translated from German)

Hey, Yeah, it was like my car was haunted with all those weird symptoms! To answer your question, fixing the wiring harness set me back by 155€, but it was worth every cent. The good news is, once the harness was fixed, all the glow control unit problems vanished. Miracle, huh? No more troublesome black smoke, the glow light stopped acting crazy on me, and even the cold starts became smoother. Basically, the car got its mojo back! Just remember to catch it early and get it fixed by a competent mechanic. Don't want that bad boy turning into a money pit. In my experience, it’s better to burn a bit of cash now than a whole load later. Keep me posted on how it goes, will ya? Good luck!

(Translated from German)

Hey, Thanks a lot for those reassuring words! Yeah, it seriously feels like my ride's possessed or something. Haha! 155€, huh? Sounds like a fair trade to get the car running smoothly again. I'm relieved to hear that it corrected all the issues you were facing. Gives me hope that it might just do the trick for my old gal as well. I’m going to ring up a few mechanics today and fingers crossed, I'll find a competent one this time around. I understand what you mean. We've got to spend a bit to save a lot, right? You've been a huge help! I'll be sure to let you know how it goes. Wish me luck! Cheers!

(Translated from German)