2012 Lexus IS Diesel Issues: Black Smoke, Difficulty Starting, Shaking at Idle, and DPF Regeneration Problems

Hey! I reckon I can help you out here. I had a comparable issue with my 2010 Lexus IS, a touch different model but similar brand. I fancy myself having some car experience, definitely not an expert but I can hold my own under the hood. What eventually nailed the issue for my ride was replacing the wiring harness from the glow control unit to the digital diesel electronics. This wasn't an off-the-bat diagnosis though, the workshop had me stumped for a while. Long story short, after this fix, the car was rearing to hit the road again and cost me about 155 Euro. I'd say, based on the symptoms you're describing, there's a fair chance you might be facing a similar problem. Just curious could you share your car's mileage, maintenance history, and if there were any recent repairs done? With more info, I could share further insights. Keep that chin up, we'll get your beast revving again! Cheers!

Thanks for your advice! So great to have someone who's been through similar struggles. My Lexus hit the milestone of 101029 KM recently. Regarding maintenance, I get it serviced regularly, and the latest service was just a couple of months back. No major repairs done recently, just the usual upkeeps, oil change, filters, etc. I'll mention this wiring harness affair to my mechanic, see what he reckons. Thanks a bunch again, hope to get my beauty purring like a kitten real soon! Cheers.

Hey there, top thanks for the additional details! Always helps to put things into perspective. Now, you know, given your car's mileage and its standard maintenance, some wear and tear are expected. Considering all the symptoms you’ve mentioned like the black smoke, longer cold start time, DPF regen failure, and the others; you might definitely want to relay the instance of my wiring harness replacement. The glow plug control module wiring harness, if defective, can actually contribute to all these issues you've been having. Worth mentioning though, be prepared, the mechanic might want to do some further checks as these symptoms can also be indicative of other issues like a clogged DPF, faulty injectors, or even a failing EGR valve. But like I said earlier, my gut says it's the wiring harness issue like I had. Keeping my fingers crossed for you. Hope your Lexus is soon back on track running as smooth as ever. Just remember, the important thing here is to trust the professional’s diagnosis. I’m here for any further chat! Cheers!

That's really insightful. Thanks a ton! I've made a note of all the potential issues you mentioned which might be causing these symptoms. I'll make sure to have a detailed chat about these with my mechanic before he starts digging into things. Definitely, will trust the professional's diagnosis, but it's pretty handy to have a little heads-up from you. Thanks again for the valuable input and the encouraging words. This ol'gal and I will be back on the road in no time, purring and powerful! Cheers.