Mercedes X Klasse diesel exhaust back pressure sensor issue

I understand your concern regarding the Mercedes X Klasse and the exhaust system malfunction you are experiencing. It sounds as though your initial assessment is plausible. A defective exhaust back pressure sensor is indeed a common culprit behind the symptoms you described, particularly the illuminated warning light, smoke emission during acceleration, and the inability to initiate DPF regeneration. I had a similar issue on my X Klasse, although it presented slightly differently at first. Before definitively concluding that the sensor is faulty, have you considered inspecting the exhaust system for any physical damage, such as leaks or blockages, that could influence the back pressure readings? Additionally, it would be prudent to verify the electrical connections to the sensor to rule out any wiring issues. Furthermore, what diagnostic trouble codes (DTCs) are being reported by the vehicle's onboard diagnostics system? Providing this information will assist in making a more informed determination.

Thanks for the detailed reply! I haven't actually checked for physical damage to the exhaust system itself, I'll take a look tomorrow. The diagnostic code is P2453 - Diesel Particulate Filter Pressure Sensor Range/Performance. Does that solidify the sensor being the issue?

The presence of DTC P2453 does strongly suggest a problem with the diesel particulate filter pressure sensor or its associated circuitry. Given the symptoms you initially described, coupled with this specific DTC, it is highly probable that the exhaust back pressure sensor is indeed the source of the malfunction. While you can attempt to inspect the wiring and connections, replacing the sensor is likely the next logical step. That said, I would still advise seeking assistance from a qualified technician. A workshop will be able to perform a comprehensive diagnostic assessment and replace the sensor, ensuring correct installation and calibration. They can also confirm there are no underlying issues affecting engine performance or vehicle emissions.

Took it to the workshop, and you were spot on! It was the exhaust back pressure sensor. New one fitted, cost me 245€, and all the problems are gone. Thanks for your help!