Stop / Start (ECO) not restarting engine

[merc07]

I will.have to check that fuse connection on mine, see if it is causing the green light to go out now and again on mine - although I doubt it as Merc and Indy have failed to fix it in the past so it can't be that simple..

iCarsoft only shows the start stop data for the 250 - for the 350, start stop is another function that doesn't show up..

 

[merc07]

I will.have to check that fuse connection on mine, see if it is causing the green light to go out now and again on mine - although I doubt it as Merc and Indy have failed to fix it in the past so it can't be that simple..

iCarsoft only shows the start stop data for the 250 - for the 350, start stop is another function that doesn't show up..

Not sure what engine he has, can't find a mention anywhere ?

 

[MrGreedy]

I made the assumption in post#5 that it's the OM651. This is based on the OPs profile showing a C250, which looks like a W204 (2007-2014).
The W204 was facelifted 2011-2014 according to Wikipedia, at which point all models received stop/start.
Prior to facelift, apparently only C 180 CGI BlueEfficiency, C 200 CGI BlueEfficiency and the C 220 CDI BlueEfficiency models had ECO stop/start.
But we've had no confirmation.

 

[dazblink]

Not sure what engine he has, can't find a mention anywhere ?

Sorry, I got a 2012 C 250 (204.203) CDI

 

[dazblink]

iCarsoft can show the state of the Stop/Start parameters. Might be worth reading the live data while the car is driven and stopped, to see if any of the parameters is showing implausible data.

I have found this data. At this point I had pulled up with ECO light green and the ECO kicked in stopping the engine. This was prior to attempting to pull away when the engine 'should' start back up. (it didn't start back up btw - I had to disconnect and reconnect the battery)

I'm not entirely sure what i'm looking at but I see that the status of the button N72/1s50 is not actuated / not active?

 

[markjay]

It seems that your Stop/Star deactivates itself. This normally happens when the battery is discharged, or when one of the perquisite components is faulty and provides implausible data. It's odd that it happens exactly when Stop/Starts tries to restart the engine, possibly there's something in the starter motor operation that triggers a failure of the Stop/Start, perhaps due to excessive current draw. Can you post the other (unrelated) fault codes? Also, which model of battery did you fit, and has it been tested - what voltage does it show when the car won't start? And, you should be able to go further into the various options on iCarsoft, e.g. 'requirements for automatic engine start', and look for any clues there.

 

[MrGreedy]

If you go into "Eco stop/start - requirements for automatic engine start" what do you seen?

Or can you view all live data for this system when running, and then see what happens after the stop?

 

[dazblink]

It seems that your Stop/Star deactivates itself. This normally happens when the battery is discharged, or when one of the perquisite components is faulty and provides implausible data. It's odd that it happens exactly when Stop/Starts tries to restart the engine, possibly there's something in the starter motor operation that triggers a failure of the Stop/Start, perhaps due to excessive current draw. Can you post the other (unrelated) fault codes? Also, which model of battery did you fit, and has it been tested - what voltage does it show when the car won't start? And, you should be able to go further into the various options on iCarsoft, e.g. 'requirements for automatic engine start', and look for any clues there.

The other fault codes are:
P200A75 The charge movement flap (cylinder bank 1) has a malfunction. The emergency position was not reached.
P208027 Temperature sensor 1 'Exhaust system' (cylinder bank 1) has a malfunction. The signal change rate is above the permissible limit value.

The 2nd one is strange one because I have replace the temp sensor but its still coming up! I was going to create another thread about these. It was only a cheap sensor so it could be that the new sensor is a dud.

The battery is a Varta F21 AGM type 110. I've not tested the battery voltage, I will go and test that on my lunch break in a bit. I will check the requirements for automatic engine start whilst I am at it.

 

[markjay]

The other fault codes are:
P200A75 The charge movement flap (cylinder bank 1) has a malfunction. The emergency position was not reached.
P208027 Temperature sensor 1 'Exhaust system' (cylinder bank 1) has a malfunction. The signal change rate is above the permissible limit value.

The 2nd one is strange one because I have replace the temp sensor but its still coming up! I was going to create another thread about these. It was only a cheap sensor so it could be that the new sensor is a dud.

The battery is a Varta F21 AGM type 110. I've not tested the battery voltage, I will go and test that on my lunch break in a bit. I will check the requirements for automatic engine start whilst I am at it.

IF the starter engine puts the battery in deep discharge then this might explain why Stop/Start deactivates itself.

But I think the issue is that with a car that has a history of electrical issues, it might be difficult to pinpoint the current fault.

One other question - you said the front SAM has been replaced - does the new unit have the same part number as the old unit, and has it been coded to the car?

 

[wongl]

It seems that your Stop/Star deactivates itself.

The OP's problem is that the Start/Stop deactivates itself during a start/stop cycle! It stops the engine (as all conditions met) but then fails to restart the engine when the OP triggers a restart. The fault is such that the OP needs to disconnect the main battery before the car can be restarted manually!!!

This is a most unusual fault as start/stop is designed to restart the car should a condition fails to be met during the stopped cycle.

 

[dazblink]

IF the starter engine puts the battery in deep discharge then this might explain why Stop/Start deactivates itself.

But I think the issue is that with a car that has a history of electrical issues, it might be difficult to pinpoint the current fault.

One other question - you said the front SAM has been replaced - does the new unit have the same part number as the old unit, and has it been coded to the car?

I didnt realise it needed to be coded to the car as its only box of fuses?

This is the one that I bought: (AS) MERCEDES BENZ W204 C CLASS ENGINE BAY FUSE BOX BATTERY TERMINAL A2075402550 | eBay

Pretty sure I checked the part numbers properly.

 

[markjay]

I didnt realise it needed to be coded to the car as its only box of fuses?

This is the one that I bought: (AS) MERCEDES BENZ W204 C CLASS ENGINE BAY FUSE BOX BATTERY TERMINAL A2075402550 | eBay

Pretty sure I checked the part numbers properly.

Was it a box like this:?

 

[markjay]

Re coding, see for example:

W204 Coding of Front SAM

1

mhhauto.com

 

[markjay]

The front and rear SAM units manage the delivery of power to the various electrical consumers. Cars have many optional items, so the SAM needs to be coded to the car's VIN. Once this is done, the SAM reads the car's unique option list from the Datacard, and activates those options that are applicable to the car. If the SAM isn't coded correctly, then these two things may happen: options that the car has won't work, because the SAM doesn't know about them and they are showing as not-installed and therefore deactivated on the SAM, and/or the SAM will look for options that don't actually exist on the car and when these options do not respond the SAM will think they are faulty and flag-up an error. That said, I don't know if your Stop/Start fault is related to the SAM coding.

 

[dazblink]

Was it a box like this:?

Nope Its the one close to the battery. This one....

 

[dazblink]

Just had a play with it on my lunch. Activated the stop/start numerous times by driving around the block and coming to a standstill on the works car park.

- 1st time the eco kicked in I had to disconnect the battery as I have been doing.
- 2nd and 3rd time it stalled like normal when starting up again but these times I didn't have to disconnect the battery. I just turned off the ignition put it in park then it started as normal on the key!
- 4th and 5th time it actually restarted automatically!! (This is the first time this has happened since my troubles) BUT I was on a slight slope at the time and it struggled and couldn't manage to get up the slope! I was revving but not going anywhere fast.
- 6th time I did it there was no restart and I had to disconnect the battery!

I tested the voltage 13v when running, 12v when engine was off (whether be it during stop start or normal start)

I checked the data on requirements for automatic engine start with these results (notice everything ok except 'on board electrical system - Not OK'

 

[markjay]

So there's an issue with the electrical system elsewhere.... which confuses the Stop/Start.

Not surprising, perhaps, given that the car has a history of electrical damage and faults.

It could be one if many things, including a faulty battery management module, alternator, starter or solenoid, etc.

I suggest that you either go through every option on iCarsoft trying to find a fault... or take the car to a specialist with STAR who knows how to diagnose electrical faults.

Regarding the SAM coding, perhaps someone more knowledgeable in these matters will come along an advise if this could be related to the Stop/Start issue.

EDIT: have you scanned to TCU for faults codes?

 

[dazblink]

So there's an issue with the electrical system elsewhere.... which confuses the Stop/Start.

Not surprising, perhaps, given that the car has a history of electrical damage and faults.

It could be one if many things, including a faulty battery management module, alternator, starter or solenoid, etc.

I suggest that you either go through every option on iCarsoft trying to find a fault... or take the car to a specialist with STAR who knows how to diagnose electrical faults.

Regarding the SAM coding, perhaps someone more knowledgeable in these matters will come along an advise if this could be related to the Stop/Start issue.

EDIT: have you scanned to TCU for faults codes?

Yeah no faults on TCU.

I've taken the 7.5A fuse out for now as somebody suggested yesterday. At least I don't have to worry about having to remember to turn it off on every trip now!

 

[MBenzUser]

I have a similar issue with my 2015 W205 C300 except it doesn't require battery disconnect. It has intermittent trouble restarting from an ECO Stop. The dashboard lights come on and the car won't restart. I then have to place push the KEYLESS-GO ON/OFF button to restart. The odd thing is it is intermittent. If ECO start/stop is turned off, it is not an issue however if you forget you could stall at a light unexpectedly. It never has an issue starting when I first enter the car.

I changed the starter last year after it failed so it is fairly new. The auxiliary battery was changed 2 yrs ago, the main battery and battery sensor are new as well. I took it to the dealer for a Xentry scan and they did not find any codes. They thought the voltage dip limiter might be failing since this starting issue doesn't occur outside of the ECO Start / Stop process. That voltage dip limiter on the positive terminal was changed but the problem still persists. I have a video link below.

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I was also reading about the auxiliary transmission oil pump and its role. Has anyone seen that fail intermittently without any codes in Xentry or OBD? What would be the pattern of failure? Would it prevent the car from activating eco/start-stop in the first place or causing a failure on restart coming out of an ECO stop if fluid pressure is low? How does it overcome that if you manually stop and restart the car?

 

[stompa]

Yeah no faults on TCU.

I've taken the 7.5A fuse out for now as somebody suggested yesterday. At least I don't have to worry about having to remember to turn it off on every trip now!

Did you ever resolve this?

my s212 e250 just started not doing stop start.

Icarsoft showed the same “on board electrical system - Not OK” message.

there where 2 additional historical faults related to bonnet sensor which I will attribute to its recent service but the stop start issue started before the service.

I cleared those historical message, restarted the car and stop start is now workin.

im not sure what “on board electrical system - Not OK” relates to as u. Pull not find any additional faults via icarsoft.