Mercedes C350E - issues with 12V Battery Module and switching to E-mode

Page may contain affiliate links. Please see terms for details.

MCINERJ

New Member
Joined
Jul 7, 2020
Messages
10
Location
London
Car
C350E
Have had a few issues recently with my car, not being able to switch into E-mode and hybrid not switching into electric either, took it to an independent who plugged it in to diagnostics, came up that the High Voltage Battery Module needed replacing.

car is 3 and half years old, and has 27,100 miles on the clock

Took it into dealership and they are saying that there is an issue with the 12V battery module, been given a nice bill of 750 pounds, explanation says : Hybrid fault : 12V battery replace, software update and retest.

any thoughts? has anyone had anything similar?
 
I thought these cars had something larger than a 12v battery
 
Have had a few issues recently with my car, not being able to switch into E-mode and hybrid not switching into electric either, took it to an independent who plugged it in to diagnostics, came up that the High Voltage Battery Module needed replacing.

car is 3 and half years old, and has 27,100 miles on the clock

Took it into dealership and they are saying that there is an issue with the 12V battery module, been given a nice bill of 750 pounds, explanation says : Hybrid fault : 12V battery replace, software update and retest.

any thoughts? has anyone had anything similar?
Did the dealership fix your fault for £750? If so what is the problem or resolution you are after?
 
Have had a few issues recently with my car, not being able to switch into E-mode and hybrid not switching into electric either, took it to an independent who plugged it in to diagnostics, came up that the High Voltage Battery Module needed replacing.

car is 3 and half years old, and has 27,100 miles on the clock

Took it into dealership and they are saying that there is an issue with the 12V battery module, been given a nice bill of 750 pounds, explanation says : Hybrid fault : 12V battery replace, software update and retest.

any thoughts? has anyone had anything similar?
Hi. I am experiencing exactly the same problem on my C 350 Te with 40000km total . The E mode will not connect and so the petrol engine will run all of the time. However, after charging the High voltage Li.ion battery, the E mode would connect, and all is ok. However, the next day E mode would not connect, Will take the car to the MB dealer on Friday nov 20, and maybe the Star diagnosis will turn out similar to yours. ? Car is still under warranty ( 2017 ) . I have checked the ( workshop) menu in the instrument display, and Battery BN is pending between 48-0 and the voltage of the 12v battery is approx 11.5 with ignition ON , no engine start. Could be a poor 12v battery condition causing the E mode issue....my thoughts... or a battery module issue...
 
Hi. I am experiencing exactly the same problem on my C 350 Te with 40000km total . The E mode will not connect and so the petrol engine will run all of the time. However, after charging the High voltage Li.ion battery, the E mode would connect, and all is ok. However, the next day E mode would not connect, Will take the car to the MB dealer on Friday nov 20, and maybe the Star diagnosis will turn out similar to yours. ? Car is still under warranty ( 2017 ) . I have checked the ( workshop) menu in the instrument display, and Battery BN is pending between 48-0 and the voltage of the 12v battery is approx 11.5 with ignition ON , no engine start. Could be a poor 12v battery condition causing the E mode issue....my thoughts... or a battery module issue...

Hi. I am experiencing exactly the same problem on my C 350 Te with 40000km total . The E mode will not connect and so the petrol engine will run all of the time. However, after charging the High voltage Li.ion battery, the E mode would connect, and all is ok. However, the next day E mode would not connect, Will take the car to the MB dealer on Friday nov 20, and maybe the Star diagnosis will turn out similar to yours. ? Car is still under warranty ( 2017 ) . I have checked the ( workshop) menu in the instrument display, and Battery BN is pending between 48-0 and the voltage of the 12v battery is approx 11.5 with ignition ON , no engine start. Could be a poor 12v battery condition causing the E mode issue....my thoughts... or a battery module issue...
 
Hi Tebe, what was the outcome after putting it on the diagnostics? I bought a 2016 c350e 4 months ago and having a similar issue. Car will charge and shows 11 miles of e power but will not run on electric. I can select e-mode but petrol engine always kicks in. My wife uses the car for work which is only 2 miles from home. So at present, no electric miles and petrol only returning 24 / 25 mpg.
 
Hi Mustdash
As I expected initially, this is a poor 12v battery issue .
The 12 v battery was replaced, and now all is perfect . E mode can be selected anytime , and all is normal and behaving like a new car. Kind regards v from Tebe
 
Hi Mustdash
As I expected initially, this is a poor 12v battery issue .
The 12 v battery was replaced, and now all is perfect . E mode can be selected anytime , and all is normal and behaving like a new car. Kind regards v from Tebe
Great results! Thank you for posting the outcome back on here.
 
Hi Mustdash
As I expected initially, this is a poor 12v battery issue .
The 12 v battery was replaced, and now all is perfect . E mode can be selected anytime , and all is normal and behaving like a new car. Kind regards v from Tebe
I noticed that the OP had a new battery and a software update. Did yours get a software update, too, or was it just the new 12V battery that was needed?
 
Hi Tebe, thanks for your reply. I was hoping that would be the case. I'll get mine tested next week and will post again afterwards. Did you have to have a software update as well or just a simple battery change?
 
Hi Tebe, thanks for your reply. I was hoping that would be the case. I'll get mine tested next week and will post again afterwards. Did you have to have a software update as well or just a simple battery change?
what was the outcome for you mustdash, my c350e as started doing this today and the cooling fan is on full speed even from cold,coolant is correct temperture etc
 
what was the outcome for you mustdash, my c350e as started doing this today and the cooling fan is on full speed even from cold,coolant is correct temperture etc
Hi Smythe... Luckily mine was just a battery issue and once a new one was put on, everything was OK. Hope you get yours sorted. When I got it back, made me feel like I'd got a new car😁
 
Hi Tebe, thanks for your reply. I was hoping that would be the case. I'll get mine tested next week and will post again afterwards. Did you have to have a software update as well or just a simple battery change?
what was the outcome for you mustdash, my c350e as started doing this today and the cooling fan is on full speed even from cold,coolant is correct temperture etc
Hi Smythe... Luckily mine was just a battery issue and once a new one was put on, everything was OK. Hope you get yours sorted. When I got it back, made me feel like I'd got a new car😁
I hope its the same for me ,mines a september 2016 car and don't get the use it should(it can sit for a week or more at a time) ,if so i wont be getting a mercedes battery but a varta own brand one ,would you know what battery was fitted to yours
 
what was the outcome for you mustdash, my c350e as started doing this today and the cooling fan is on full speed even from cold,coolant is correct temperture etc

I hope its the same for me ,mines a september 2016 car and don't get the use it should(it can sit for a week or more at a time) ,if so i wont be getting a mercedes battery but a varta own brand one ,would you know what battery was fitted to yours
I can have a look tomorrow and let you know. To be fair, the Merc dealership charged £168 plus VAT for the battery, which isn't a million miles from a varta brand.
 
what was the outcome for you mustdash, my c350e as started doing this today and the cooling fan is on full speed even from cold,coolant is correct temperture etc
Hi

I've seen this issue before where the cooling fan runs at full speed even when it's cold and it's to do with the lin communication line to the fan unit
It suggests from corrosion below the brake booster and causes the voltage to drop on the lin line and thus the fan goes into emergency running mode
 
I can have a look tomorrow and let you know. To be fair, the Merc dealership charged £168 plus VAT for the battery, which isn't a million miles from a varta brand.
In that case i don't mind ,i just checked prices on GSF & ECP and there over £400 (i know they have a constant discount) but still alot was your price supply only ,many thanks
 
Hi

I've seen this issue before where the cooling fan runs at full speed even when it's cold and it's to do with the lin communication line to the fan unit
It suggests from corrosion below the brake booster and causes the voltage to drop on the lin line and thus the fan goes into emergency running mode
That will be my luck ,can i visually see the corrosion in the engine bay area should it be that
 
That will be my luck ,can i visually see the corrosion in the engine bay area should it be that
Not the easiest if I'm honest the last one I did with this similar issue the abs and brake booster units had to be removed and the loom untapped and checked manually. Best to get the vehicle on the xentry machine and check the fault codes if it comes up with lin communication errors then there stands a chance that's the issues but there are other components on the same circuit so all would need to be checked
 
Not the easiest if I'm honest the last one I did with this similar issue the abs and brake booster units had to be removed and the loom untapped and checked manually. Best to get the vehicle on the xentry machine and check the fault codes if it comes up with lin communication errors then there stands a chance that's the issues but there are other components on the same circuit so all would need to be checked
I guess its the usual , plug it in first job , could do without this atm but as to be
 
Hi Tebe, thanks for your reply. I was hoping that would be the case. I'll get mine tested next week and will post again afterwards. Did you have to have a software update as well or just a simple battery change?
Hi again Mustdash. As far as I know, only the 12 V battery was replaced. The dealer always check the system for any error codes by using the diagnostic scanner tool. Nothing else but the battery replacement was mentioned when I picked up the car at the dealer.. Warranty job in Norway as we are happy to get a full 5 years warranty for all vehicle brands in Norway, except from Kia = 7 years warranty like in all other countries in Europe...
 

Users who are viewing this thread

Back
Top Bottom