Justy Diesel Power Loss: Filter or Sensor Problems

I had a similar issue with my 2007 Subaru Trezia diesel a couple years back. Based on my experience with a few diesel cars, these symptoms definitely sound familiar. The main signs were exactly like yours, power loss and smoke, especially during acceleration. The workshop diagnosed a completely clogged DPF that was causing excessive backpressure in the exhaust system. They first attempted DPF cleaning and forced regeneration, but ultimately the diesel filter was too damaged and needed full replacement. The total repair cost was 1550€, which included diagnostics, labor and the new DPF. Since then, no more smoke or power issues. The engine response improved significantly after the filter replacement. Before suggesting specific solutions, it would help to know: current mileage on your Justy, any warning lights on the dashboard, Type of driving you mostly do (city/highway), When was the last DPF regeneration performed, Service history regarding the particle filter With this information, we could better determine if your symptoms match what I experienced and whether you might need similar repairs. As a preventive measure, consider having regular DPF cleaning services to avoid complete filter failure in the future.

Thanks for your follow-up. My Justy has 119542 KM on the clock, with the most recent service completed just last month. No warning lights showed up on the dashboard initially, though a check engine light appeared yesterday. The vehicle inspection from my last service didnt show any sensor faults, but the smoke and power loss started about 2 weeks after. I mostly do short city trips, rarely hitting highway speeds. Never had any diesel filter work done before, so your DPF theory makes a lot of sense given the symptoms and driving pattern. I will get it checked at a workshop focusing on the exhaust system and filter replacement options you mentioned. The repair cost you shared helps set realistic expectations for the potential work needed.

Good to hear back and thanks for those details. My Trezia had similar mileage when the DPF issues started, and the short city trips pattern matches my situation exactly. Those frequent short trips definitely contributed to my DPF problems since the diesel filter needs longer drives at sustained speeds to complete proper regeneration cycles. The lack of previous filter maintenance combined with city driving is a classic recipe for DPF clogging. The check engine light appearing matches my experience too. In my case, it started about a week after the initial power loss symptoms. The sensor fault eventually showed up in the diagnostic scan, confirming excessive backpressure from the clogged filter. During my repair, the workshop mentioned that waiting too long after these symptoms appear can lead to more expensive repairs if the exhaust system gets damaged. Getting it checked soon was definitely the right call in my case. Since your driving pattern is similar, consider asking the workshop about preventive regeneration options after the repair. My mechanic programmed more frequent regeneration cycles which helped manage the issue with my mainly city driving routine.

Thanks for all that helpful input. Just wanted to update that I took the car in today, and you were spot on, it was indeed a severely clogged diesel filter. The workshop did a full vehicle inspection and found the DPF was operating at only 15% capacity, severely impacting fuel efficiency. The exhaust system showed significant carbon buildup, but fortunately no permanent damage. They performed DPF cleaning first, which partially improved things, but ultimately recommended replacement due to the internal damage found during inspection. The total cost came to 1350€, slightly less than what you paid, which included the new filter and labor. The fuel efficiency has improved noticeably, and the smoke is completely gone. The engine pulls much stronger now too. They also adjusted the regeneration settings to better suit my city driving pattern, just as you suggested. Really appreciate the guidance, it helped me approach the workshop with a better understanding of the likely issues and expected costs.