Just had another failure of the downstream NOx sensor in my 2019 GLC 250d, had a diagnostic done at home then confirmed by Mercedes Inverness. This sensor was replaced in June 2022 and was done foc as a goodwill gesture as it was just out of warranty. No luck this time though even though the sensor is only 2 1/2 years old and has only done over 20,000 miles , not quite the quality I’d expect from an alleged premium brand but all too common. Anyway when it was in for the diagnostic check they carried out a software update which I didn’t know was going to be carried out until the work started but since this was done ( over a month now ) there has been no EML light showing up. This is all fine and well but they did confirm the sensor needs replacing after the diagnostic test so I guess it’s just a matter of time before it comes on again. See attachment for details of the software update.
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