VW T5 DPF Warning, Critical Low Pressure Problem

I had a similar issue with my VW T6 2.1 TDI last year, and having dealt with several diesel engine repairs before, I can share my experience. The symptoms you describe match what I encountered, power loss, warning lights, and emission control problems. The exhaust back pressure sensor was diagnosed as defective, causing incorrect readings for the particulate filter system. After replacement and recalibration at a specialized diesel workshop, the DPF issues were completely resolved, costing 245€ for parts and labor. Before jumping to conclusions though, could you share: Complete engine code, Current mileage, How long the symptoms have been present, Any recent DPF regeneration attempts, Previous service history regarding the exhaust system This information would help determine if your case is similar. A faulty pressure sensor often mimics more serious DPF issues, but its worth confirming the exact cause before proceeding with repairs. The diagnostic approach should start with verifying sensor readings before considering more extensive exhaust system work. The repair in my case took about 3 hours, including diagnostic time and road testing to ensure the emission control system was functioning properly.

Latest service was 2 months ago at 102000km. The symptoms started appearing gradually over the past 3 weeks. The engine code is CAAB, and no regeneration attempts have been made yet. The exhaust system was last checked during the service and appeared normal at that time. The workshop did mention the DPF pressure sensor values were within normal range during the service, which makes me wonder if the issue developed rapidly afterward. No previous exhaust-related repairs are documented in the service history. This sudden change in diesel exhaust behavior is concerning, especially since everything was fine during the recent checkup. The low pressure readings now showing up seem to indicate a rapid deterioration of some component in the system. Would it be worth trying a forced regeneration first, or should I skip straight to having the pressure sensor checked given the quick onset of these symptoms?

A forced DPF regeneration might not address the root cause here. Your symptoms developing so rapidly after a clean service check suggests the pressure sensor readings could be misleading. When my exhaust system started showing similar issues, the initial pressure readings also appeared normal before suddenly indicating problems. The rapid onset of symptoms combined with smoke during acceleration points toward a potential issue between the pressure sensor and the DPF control module. In my case, the sensor was intermittently failing, showing normal values during the service but later causing the diesel engine to enter limp mode. Before spending money on a full DPF regeneration, I would recommend: 1. Getting the pressure sensor thoroughly tested under various load conditions 2. Having the electrical connections to the exhaust back pressure sensor checked 3. Verifying the DPF differential pressure readings during acceleration The repair cost was reasonable in my case at 245€, and it resolved both the power loss and smoke issues. The low pressure readings cleared up immediately after the sensor replacement, and the engine performance returned to normal without needing a forced regeneration. Consider requesting these specific diagnostic checks at your next workshop visit. The CAAB engine code has similar DPF system design to mine, so the repair approach should be comparable.

Thanks for the detailed response. Based on your feedback, I will schedule a diagnostic check focusing on the pressure sensor and electrical connections first. The timeline matches what you experienced, normal readings at service followed by rapid symptom development. The exhaust system behavior does sound quite similar to your case, especially the combination of visible smoke and power loss. Since the particulate filter was fine during the recent service, a sudden failure seems less likely than a sensor issue. I will avoid the DPF regeneration for now and have the workshop check the differential pressure readings under load as you suggested. The repair cost of around 245€ seems reasonable if it resolves both the low pressure warnings and performance issues. One quick question though, did you notice any improvement in diesel exhaust smoke immediately after your sensor replacement, or did it take a few driving cycles for the system to normalize?