Seeking Advice on Resolving Black Smoke, Drop in Power, Exhaust Leak and Unpleasant Odor in 2003 Lexus GX's Gasoline Engine

Hey there! Seems like we've got a pretty similar problem, had the same issue on my 2005 Lexus RX. I'm not an expert but I do have a decent understanding of cars from tinkering around with mine a fair bit. The issue in my case was due to one of the lambda sensors being defective. It ended up costing me 375€ to fix it at my trusted local garage. They sorted it out by replacing the faulty sensor. Mind you, it's always a good idea to check your vehicle at a proper facility to make sure the exact cause is identified. May I know the specific model you're driving and its mileage? Maybe I can provide more detailed help with that information. Hope this was helpful!

Thanks for the reply. My GX has racked up about 86404 KM on the odometer till now. My latest service was over 8 months ago. You reckon it might be time for another service visit considering the mileage and these symptoms? Might just get the lambda sensors checked out during the service. Cheers!

Hey, given the symptoms you described and the mileage on your GX, I'd definitely recommend checking out that lambda sensor. When mine went bad, it caused a similar combination of issues including the check engine light and the black smoke. A bad sensor can mess with the fuel-air mixture, causing the engine to run rich, which might explain the black smoke and power loss you're experiencing. Your GX might also benefit from a general service check-up considering it's been 8 months since the last one. Besides the lambda sensor, they can check out the overall health of the vehicle, including the exhaust system, which might address your concern about the potential exhaust aftertreatment malfunction. Do keep us posted on how things turn out. All the best!

Hey there, thanks for that insight! It certainly makes sense, the sensor messing about with the fuel-air mixture could indeed be causing the engine to run rich, hence the smoke and power loss. Definitely seems like it's time for a general service check-up and I'll get them to thoroughly check the exhaust system along with the lambda sensor. Will keep you fellas posted on the progress. Cheers and thanks again!