Mercedes S Klasse Diesel Smoke and DPF Issues

I'm getting seriously frustrated with my 2013 Mercedes S Klasse diesel. Only 65996 km on the clock! The warning light popped up, and now it's blowing smoke like a chimney when I accelerate. My mechanic says the DPF isn't regenerating. He suspects it's the exhaust back pressure sensor. Has anyone else had this issue? Is it a common maintenance problem on these models? He quoted me about 245€ for the repair including a new exhaust sensor. This sucks!

4 comment(s)

Sounds familiar. I had similar symptoms on my S Klasse. I'd also check the pressure sensor itself. Sometimes the wiring harness gets brittle and cracks, causing a bad reading. Is he sure the sensor is faulty and not just a wiring issue throwing things off?

Good point! I'll ask him to double-check the wiring before replacing the sensor. Is there a way to test the sensor with vehicle diagnostics to be absolutely sure? I'd hate to spend the money for nothing!

Yeah, a proper scan tool should give live readings from the exhaust sensor. If it's reading way out of range, even with the engine at idle, that's a strong indicator. Replacing the sensor fixed my similar problem; it's like night and day now. If the sensor is bad, it's like trying to run a marathon with a blocked nose – the car just can't breathe properly.

Thanks a million! I really appreciate the help. The mechanic confirmed it was indeed the exhaust sensor after checking the wiring. Got it replaced, and the smoke is gone, the warning light is off, and the DPF is regenerating again. That pressure sensor was definitely the culprit. 245€ well spent!

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