Mercedes C Klasse Hybrid Exhaust Back Pressure Sensor Issue

Interesting problem. I own a C Klasse as well. Your situation sounds awfully familiar to a problem I had a while back. The symptoms you describe, the warning light, the smoke, the DPF issue, they all scream exhaust back pressure sensor. Before you commit to the repair, could you elaborate on how the diagnostics were performed? Was it a simple OBDII code read, or was there more in-depth analysis of the sensor's readings under various engine loads?

The diagnostics were performed at a local garage. They used a standard OBDII reader initially, which flagged the exhaust back pressure sensor. Then they used a more advanced diagnostic tool to monitor the sensor's real-time output while revving the engine. The readings were erratic and inconsistent, further suggesting a faulty sensor. Is this consistent with your experience? Did you also observe similar sensor behavior before replacing it? Did replacing the pressure sensor resolve all the symptoms related to engine performance and emission control?

Yes, that diagnostic process aligns with what I went through. Erratic readings under load are a strong indicator. Given your description, it does appear that the exhaust back pressure sensor is indeed the primary issue. While it's always wise to consider other possibilities, the symptoms and diagnostics strongly point in that direction. My advice would be to proceed with replacing the sensor. It's a relatively inexpensive repair, and it should resolve your issues. I would suggest you let the workshop do the repair. What do you think?

Thank you for the helpful advice and for sharing your experience. Replacing the exhaust back pressure sensor indeed resolved all the issues. The warning light is gone, the smoke is no longer present during acceleration, and the DPF regeneration is now functioning correctly. The car runs like new. Your insights were invaluable in confirming the diagnosis and giving me the confidence to proceed with the auto repair. Much appreciated!