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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 23617
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Class Eco start/stop playing up, it has been to dealer three

Customer Question

B-Class Eco start/stop playing up, it has been to dealer three times but they cannot (will not?) tell me what the problem is or show me a list of parameters controlling the function. Changed auxiliary battery twice, still not fixed! Any ideas?
Submitted: 12 months ago.
Category: Mercedes
Expert:  Matt replied 12 months ago.

hello

you say the start / stop is misbehaving can you tell me the sequence of events? doe it just sit there cranking the engine?

Customer: replied 12 months ago.
No, the problem is that it works for a while (days, weeks) and then stops. Dealer fiddles with it, works again, then stops. The car has been in three times, dealer either does not know how they 'Fixed' it or won't tell. Says it is very complicated, 30 or more parameters involved, refuses to provide a full list, says it is copyright. When it is working, the green light comes on almost immediately after starting the engine, when it is not working the ***** *****ght stays on for days! The car is still under warranty (another three months or so) and therefore I am minded to reject it as "not fit for purpose", although there is no other apparent fault with it.
Expert:  Matt replied 12 months ago.

Hello

the reset of the stop / start needs the use of the Mercedes STAR software so even if you had the procedure you'll still need to invest in the software

however there are a few things that can stop it form working

  • Coolant Temp too high, or too low
  • The engine has not ran for at least two minutes
  • The AC is on and not in the economy mode
  • Low Vacuum
  • Battery charge low
  • High current draw on the 12 volt system (IE defogger, defroster, and windshield wipers all on at the same time)

If one of the above conditions is met it does not allow the start stop feature to work.

so I'm wondering if your dealer has investigated all these? or are they just doing a reset and sending you on your way

as if the engine has a vacuum leak then this can come and go with temperature

I'd go back to the dealer and present them with this list and ask have they checked them all