Alfa DPF Failure Symptoms: Smoke and Power Loss Guide

I had a very similar issue with my Alfa 159 2.4 JTD from 2008. Having some experience with diesel engines, the symptoms you describe match exactly what I encountered. The reduced power and smoking during acceleration were the first signs. The workshop found that the exhaust back pressure sensor was giving incorrect readings, causing DPF regeneration issues. The faulty sensor made the system think the DPF was constantly blocked, triggering unnecessary regeneration attempts. The repair involved replacing the pressure sensor, which cost 245 Euro including labor. After replacement, all warning lights cleared and the engine performance returned to normal. The diesel exhaust system has been working perfectly since then. Before spending money on repairs, could you share: Build year of your 166, Current mileage, When was the last DPF regeneration performed, Any recent engine work or maintenance This information would help determine if your issue is identical to what I experienced. The pressure sensor failure is common on these engines, but its worth confirming the exact cause before proceeding with repairs.

Had my last service at 138882KM and experiencing the exact same symptoms on my 2000 Alfa 166 diesel engine. The DPF regeneration attempts kept failing after the warning lights appeared. The reduced power issue started gradually, but the emission control system completely malfunctioned last week. After testing, it turned out the pressure sensor was providing incorrect readings, preventing proper regeneration cycles. Getting the pressure sensor replaced solved the problem for me, total repair cost was 280 Euro. The diesel engine now runs smoothly with normal power output and no more warning lights. Based on my experience, I suggest having the sensor checked first before exploring more expensive repairs.

Thanks for sharing your repair experience. It confirms the pattern with these Alfa JTD engines, the faulty pressure sensor is definitely a common failure point that affects DPF regeneration cycles. My 159 had the exact same progression: gradual power loss followed by complete emission control system malfunction. In both our cases, the incorrect sensor readings were preventing proper DPF regeneration, leading to those typical symptoms of reduced power and smoky exhaust. The repair costs seem consistent too, I paid 245 Euro compared to your 280 Euro for the sensor replacement. The small price difference likely reflects different labor rates, but its a reasonable repair cost considering the alternative of a complete DPF system failure. For anyone else facing similar issues with JTD engines, monitoring DPF regeneration cycles and pressure sensor readings early on can help catch these problems before they cause more extensive exhaust system damage. Regular diesel particulate filter maintenance becomes even more critical once these sensors start showing signs of wear.

Thanks for the great information everyone. This has been really helpful for my Alfa 166 situation. You were absolutely right about the pressure sensor being the likely culprit. Just wanted to close this thread by confirming the repair was successful. After replacing the sensor for 280 Euro, all the DPF issues have been resolved. The particulate filter is now regenerating properly and the reduced power problem is completely gone. The diesel exhaust system is working perfectly again, no more warning lights or smoke during acceleration. Looking back, the low pressure readings were definitely the key indicator that led to the correct diagnosis. For future reference, if anyone searches this topic: checking the pressure sensor first saved me from unnecessarily replacing more expensive components. The repair cost was reasonable and fixed all the symptoms I originally posted about. Thanks again for helping identify this common fault on the JTD engines. The shared experiences made it much easier to pinpoint the issue.