Lets just assume "The reader" is correct, yes you may have a MAF Fault, but that will not cause FAN to run flat out !!
Because you aren't using SDS you can only see a tiny perecentage of what is going on, personally my experiences with guys on this forum using OBD readers suggests they tell lies, (
lol the OBD Reader lies not the forum member) 🤣 They definitely don't see even a tiny proportion of what is going on, and therefore if you own an R170 members would get a better result by asking this guy for a Diagnosis ....
Now, truthful humour aside, if you do, as we suspect, have a K40 Fault SDS won't give you a fault code for that, but a few stored faults in the modules that the OBD junk can't even see would list "No Comms with ME", and ME would have stored codes for "Low Voltage" ......................
My first port of call on any car would then be "Motor Relay", but R170 does not have separate Relays, in fact it's Motor Relay is just 1 of 5 Relays in the K40 Module, so therefore SDS Codes dependent you could have other faults if other circuits / relays within a K40 are duff. This is because the whole things are problematic now they are all at least 18 years old
Moral of the K40 story is don't faff about with it, even if you do fix it, something else will go wrong soon, so it will potentially leave you or a loved one stranded in the middle of no-where one dark and rainy night ................
Just bin it and fit a new genuine MB K40, which will then work fine for at very least the next 18 years
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