Engine ECU bad?
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Joined: Dec 2020
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2009 E63 AMG W211
Engine ECU bad?
So recently I've experienced on my E320 that a couple of seconds after starting up the engine, fan gets on the highest speed and won't stop and presumably opens the thermostat. Which allows my engine temp to sit at like 60C maximum never fully warming up, which results in higher mileage.
Well, I was convinced it would be the thermostat, so I took it to an independent which specialized in Merc, and after hooking up DAS they performed a full system diagnostics, and the Common Rail Injection came back with a -!- ... The mechanic tried to access the module to read it, but everytime it would error out saying communication was not possible. DAS itself offered some suggestions on what the cause could be:
- Check component N10/1kR (Circuit 87 relay, engine)
- Test wiring from component N3/9 (CDI Control Unit) to component N10/1 (Driver-side SAM control unit with fuse and relay). Test for short circuit and repair if necessary.
Then it also suggests to check supply at fuses 43,44 and 57.
I know that the mechanic followed this two steps, however I can not be certain if he tested it correctly, and what the results could have been.
Either way he told me this was caused by a faulty Control Unit, and that I would need to have it replaced. However my big question is, how can the car run perfectly normal with a faulty Control Unit, no lights on the dashboard, no misfiring, engine starts very quickly as well, tempomat works. And not even DAS itself suggested that Control Unit could be faulty?
Realistically, what are the chances of a fried Control Unit? Is this the case of a severed, or damaged wire and the mechanic trying to rip me off to replace the Control Unit when he knows it's just a cable or a relay as DAS suggests??
Thanks in advance
Well, I was convinced it would be the thermostat, so I took it to an independent which specialized in Merc, and after hooking up DAS they performed a full system diagnostics, and the Common Rail Injection came back with a -!- ... The mechanic tried to access the module to read it, but everytime it would error out saying communication was not possible. DAS itself offered some suggestions on what the cause could be:
- Check component N10/1kR (Circuit 87 relay, engine)
- Test wiring from component N3/9 (CDI Control Unit) to component N10/1 (Driver-side SAM control unit with fuse and relay). Test for short circuit and repair if necessary.
Then it also suggests to check supply at fuses 43,44 and 57.
I know that the mechanic followed this two steps, however I can not be certain if he tested it correctly, and what the results could have been.
Either way he told me this was caused by a faulty Control Unit, and that I would need to have it replaced. However my big question is, how can the car run perfectly normal with a faulty Control Unit, no lights on the dashboard, no misfiring, engine starts very quickly as well, tempomat works. And not even DAS itself suggested that Control Unit could be faulty?
Realistically, what are the chances of a fried Control Unit? Is this the case of a severed, or damaged wire and the mechanic trying to rip me off to replace the Control Unit when he knows it's just a cable or a relay as DAS suggests??
Thanks in advance
