Mercedes V Klasse Diesel Engine Problem Resolved

Oh man, I know that feeling! Had a similar thing happen with my old Renault Scenic – although yours is way newer. Check engine light plus sluggish performance is never good. The exhaust sensor thing rings a bell. On my Scenic, it ended up being a tiny crack in the exhaust system near the sensor. That caused temperature fluctuation messing with the readings, triggering the light and messing with the emission control. Is your exhaust unusually loud, or have you noticed any soot buildup anywhere?

Thanks for the quick reply! It isn't louder than usual, and I haven't seen any soot. Where exactly on the exhaust system was the crack on your Scenic?

On the Scenic, the crack was right where the exhaust pipe connected to the catalytic converter. Basically, the temperature fluctuation messed with the exhaust sensor. Because the ECU thought the exhaust was too hot, it pulled back on the fuel to protect the engine. That's why it felt sluggish and the consumption went up. Honestly, I'd get your Mercedes to a garage. They can smoke test the exhaust system to find any leaks. It could be something completely different than my issue, but those sensors are usually pretty reliable, and a leak is a common cause for weird readings.

Thanks. I appreciate you sharing your experience. Took it to the shop and you were right; there was a small leak in the exhaust system. They found it quickly. They replaced the exhaust sensor as well since it was already giving dodgy readings. Total cost was 265€. Running smoothly now.