Seeking Advice on '04 Fiat Stilo Diesel: Black Smoke, Power Loss, Hissing Noise, and Failing DPF Regeneration

Hey there! Had a similar issue with my '06 Fiat Bravo diesel, not too different from your Stilo. As for my car know-how, I'd say I've got some experience, though I'm far from being a pro mechanic. Based on what described, I agree with your suspicion. My issue turned out to be damaged cables on the electric changeover valve. The malfunction resembled your scenario - unusual black smoke, drop in power and the annoying engine light. My local workshop took care of it for me, friendly team and they managed to save me from a heap of stress! It ended up costing me about 155€ to get the cables replaced and everything sorted. Just asking, any specific mods or adjustments been done on your ride recently? That could give a clue. More details, especially about your car's current condition and history, might also help in giving more targeted advice. Remember, always leave this kind of stuff to the pros if you're out of your depth. Good luck!

Hey, appreciate your response. No specific mods done lately. As for my Fiat, she's got a mileage of 31481 km - quite a veteran, and her last service was pretty standard, just regular maintenance. So cables on the electric changeover valve could be causing this huh? That's a new one for me. At least it's not a hefty price to pay. Thanks for the heads up, I'll definitely discuss this with my local workshop guys. That might save me a lot of time troubleshooting. Cheers!

Hey back! Glad I could assist a bit! Your mileage is pretty decent for an '04. That kind of wear and tear might need a bit more than your standard maintenance, which could potentially be the cause of all these symptoms you're witnessing. Yeah, when it comes to the EGR type issues, the cables can sometimes be the guilty party! Who would've thought, right? It’s always worth consulting with the pros, though. They just know their stuff better and sometimes even simple things can turn out to be a bit more complicated. Hope your local workshop guys can pin it down for you directly. Keep us updated on how it turns out. We all are learning from each other's experiences here. By the way, if the problem persists after the fix, it might be worth considering an EGR delete, but that's a whole other discussion and should be regarded as a last resort. Take care good luck with the workshop!

Hey, yeah, you got that right, a bit more than standard care is due. At this moment, fingers crossed that it's really just the cables causing all the drama. I wouldn't want to climb a whole new learning curve with the EGR delete - but if it comes to that, well, what can you do! It's been great having this chat and I feel way more informed now. I will go ahead and discuss all of this with my local guys and hope they find the cure soonish. Will definitely keep you posted on how this evolves and what the actual issue was. Thanks again have a good one! Stay safe!

Code p0402 Hello, I bought a Fiat 500 1.03L Multijet diesel and I have a check engine light. When I use a diagnostic tool, I get this fault code and the car loses power then recovers, repeatedly. Can you help me?

(Translated from French)

The P0402 code indicates excessive exhaust gas recirculation (EGR) flow. Start by checking the EGR valve for any signs of sticking or blockage, as this can cause the symptoms you're experiencing. Ensure that the EGR valve and its passages are clean and free of carbon buildup. If you're comfortable, you can try cleaning the EGR valve yourself, but if the problem persists, it's best to have a professional mechanic inspect it further. Let me know how it goes or if you have any other questions!