Datum: 21. Oktober 2020 20:28
If the oxygen sensor signal shows a low value in idle mode, but at the same time at 2000 or 3000 rpm the readings change, the sensor is working properly. it does not need to be changed.
most often, the cause of this problem is an
intake air leak. There are nuances due to incorrect adaptation of the ECU, but at W124 this is a rarity (more often it can be found at W202 \ W210).
If LPG is installed, then it can also be the cause (wear)
You need to look at the parameters of the engine.
My solutions for troubleshooting Mercedes release 93-98:
Diagnose von Mercedes M104 und M111-Motoren mit einem Laptop auf eigene Faust.
Diagnosegerät (OBD2) und Reiserechner für Mercedes Motoren M111 und M104 mit HFM oder PMS auf einem Tablet/Smartphone