Greetings from Northern Europe! I have old W220 diesel from 2003 (S320CDI). Last week suddenly temperature gauge needle started to fluctuate and then went to maximum mark with gold engine. I don’t even crank my car (lock position 2). Diagnose doesn’t show any fault related to temperature sensor or something else. I unplugged sensor (assumed that no resistance and value will be minimum now) but temperature gauge goes to maximum again when I turn ignition to position 2. Temperature sensor wires go from sensor (situated on the left side near thermostat) directly to ECU so I cut off wires near ECU connector (if there were short somewhere then 5 volts would go back directly from another wire showing maximum) but nothing happened. Instrument cluster is tested and gauge itself is good, also all SAM modules. One thing I want to mention is that when I start my car it thinks that overheating is in progress and radiator fan goes in maximum turns. What else I can do or check? Maybe there is one more temperature sensor on that particular CDI engine (OM648) which maybe faulty? Can somebody help please?

 

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