Troubleshooting Black Smoke, Engine Jerking, and Fuel Economy Issues in a 2019 Hyundai i40

Hey there, I had a similar issue with my 2017 Hyundai Sonata, the 2.00 litre petrol variant. Personally, I can't call myself an expert but I have some experience with cars. At the workshop, I addressed my problem, and they did a comprehensive OBD (On-Board Diagnostic) scan first. The code pointed at a problem with the Lambda sensor. The technician confirmed it when he saw ceramic inside was all clogged/dirty which was limiting its ability to correctly measure the oxygen level; hence, the ECU was getting incorrect air/fuel mixture ratio and the fuel economy was hampered. Replacing the sensor at the workshop took care of those issues for me, including those black smoke emissions. It cost me 375 Euro but it was worth it for the fuel savings and peace of mind. About your issues, can you tell me more about the mileage on your i40, and your maintenance schedule?. Also, have you scanned for OBD Faults? I would be happy to help more with that info.

Hey, really appreciate your detailed response. My i40 has run around 35798 km till now. I usually get it serviced as per the standard recommended schedule. As for the OBD scan, haven't had a chance yet to get it done. Given your experience, I reckon I should schedule an appointment with my dealer right away and get it checked out. Thanks again for your insight!

Hello again! No problem at all, happy to share what I've learned. Yes, I'd definitely echo that sentiment – getting an OBD scan at your dealer would be a great next step. Given your mileage is pretty low, it's quite odd for the Lambda sensor to quit that early unless either the fuel you are using is not of good quality, or the sensor got damaged due to some other reason. But no worries bud, it's manageable. You're doing the right thing by taking actions quickly. Keep in mind though, prices might differ depending on your location and workshop. Try to ask them how much they would charge before the job is done to avoid any surprise costs. Let me know how it goes! Happy motoring!

Cheers! Yeah, you're right. I use fuel from a reputed vendor but I guess it's anyone's guess how these components behave. I'll set up the OBD scan at the dealer and see where that leads. Appreciate the head's up on the costs too, I'll ask for an estimate. Will keep you posted on how things pan out. Happy driving to you too!