SL/R231: Sensors
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Joined: Feb 2021
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From: Nor-Cal
2020 GLC300 -2014 Sl550 - 1997 SL600
Ok I have realised that the engine light doesn't come on after the reset but after stopping and re starting the engine. I have scanned it many times and get the same fault i.e. NOx sensor bank 2 general wiring fault. When delving deeper into it the sensor is not operational. speaking to a Mercedes independent this seems to be a common fault with the petrol engine and he advised me to have the NOx sensors remapped out. So that's the rout I'm going down. I will post in a couple of weeks when said process has been done, hopefully with good news.
That’s fairly unusual, re-mapped? Did he elaborate? Since they’re hands on, we have to have some faith in their competence. But this isn’t typical for Nox sensor replacement.
Only 40k miles? May want to also check wiring. Is it a factory MB part?
Last edited by crconsulting; Jul 26, 2025 at 10:06 AM.
Thread Starter
Member
Joined: Sep 2020
Posts: 165
Likes: 33
From: Stockport UK
SL 350 R231
OK This is what the independent said. "On a petrol car these sensors only serve to check that the Nox catalysts still work. Much like secondary02 sensors for the three way catalyst.
They do not serve any other function (mixture etc)
They do not serve any other function (mixture etc)
