halfords-pro

Evening all, some direction would be appreciated.

I recently had an issue with my recently new (but second-hand) W205 C250 Diesel (2017) failing to start when using the KEYLESS-GO button. A bit of fiddling with Xentry and moving over to the actual key appears to have resolved this problem.

I then decided to swap out the main battery as it looked like original as I thought this might have something to do with the starting issue and also a lack of ECO START/STOP (except after an hour on the motorway). I swapped what looks like a genuine Mercedes battery for an A6 VartaSilver Dynamic AGM Start-Stop Battery 12V 80Ah 580 901 080 (115AGM).

Everything works great for a day or two and then taking my wife to work this morning I get a 'replace battery in key fob error', followed a few minutes later by all of the lights on the dash coming on, followed by Active Brake Assist and ESP failure messages (see photos) and the engine cutting out. I gingerly made my way home (approx. 5 miles) with this happening 3 more times.

Went to pick-up Mrs H-P from work this evening and no issues what-so-ever, until maybe 20 mins into the drive and..... dashboard lights up and immediately goes away, engine continues to run. Then, later on the drive home, bam.... everything goes again. All the lights on the dash, ABS and ESP failure messages and the engine cuts out. Engine won't start this time and we push the Mercedes off the road. Give it five minutes and its starts again.

There aren't any similarities between this morning and this afternoon, however it happened this afternoon just as I was accelerating away from lights and again when I was going over a road hump.

I have a copy of Xentry and the common current fault codes appear to be: Communication with the control unit 'combustion engine' has a malfunction. The message is missing. I'm getting this error from the Powertrain module (PTGU), Transmission Control for 9-Speed Transmission module (VGS), Collision Prevention Assist module, Multifunction Camera module, Electrical Power Steering module.

I've checked the CAN BUS wiring for water ingress in the passenger compartment, but there doesn't appear to be any water ingress or damage. I've added several attachments which may help.

Any thoughts on what my next steps might be, other than booking into my local friendly independent?

H-P

halfords-pro

I've looked again at the fault codes I'm getting and I notice that they all talk about communication with the combustion engine module having a similar error:

N127 - Control unit 'Powertrain' (PTCU)

• U010087 - Communication with the control unit 'combustion engine' has a malfunction. The message is missing.

Y3/8 - Transmission control for 9-speed transmission (VGS)

• U010000 - Communication with the control unit 'combustion engine' has a malfunction

A90 - Control unit 'COLLISION PREVENTION ASSIST' (SG-AWF)

• U010087 - Communication with the control unit 'combustion engine' has a malfunction. The message is missing.

A40/11 - Multifunction camera (mono) (MFK)

• U010087 - Communication with the control unit 'combustion engine' has a malfunction. The message is missing.

N68 - Electrical power steering (ES)

• U010000 - Communication with the control unit 'combustion engine' has a malfunction

Checking the fault codes in the Combustion Engine module I can see the following:

N3/9 - Motor electronics 'CDID3S2' for combustion engine 'OM651' (CDI)

• P200A07 - The charge movement flap (cylinder bank 1) has a malfunction. There is a mechanical fault.
• P056013 - The on-board electrical system voltage has a malfunction. There is an open circuit.
• P056200 - The on-board power supply voltage is too low. _
• P200671 - The charge movement flap (cylinder bank 1) is jammed closed. The actuator is blocked.

Could the above errors be related to these Combustion Engine module errors, especially P056013 - The on-board electrical system voltage has a malfunction. There is an open circuit and P056200 - The on-board power supply voltage is too low?

H-P.

CaliBenzDriver

I just found your thread advertised to me... Great job digging into this perfect nightmare. Sorry to read about your struggle. Pls stay in the slow lane off from the main roads for safety!


The long story short is you either have poor voltage control or silent CAN-C disruption from ESP.
Let's figure this out.

Drive with your cluster displaying BATTERY INFO from the service menu.

See if chassis voltage deeps below 12.4V while driving.


YES: Voltage swinging from 12.55 to 14.9v are perfectly normal.

NO : Below 12.4, 12.2, 12.0, 11.8v are significant to CAN modules crashing.