My Car: MERCEDES-BENZ B-CLASS Sports Tourer (W246, W242) B180 (246.242), M270.910 Engine
1.6 Petrol Direct Injection
Mileage 73,000 km (46,000mls)


What happened?
• returned home after 8 months away;
Negative terminal was left on causing car battery to deplete and drain the Starter Battery(A0019828008) and the Auxiliary Battery(A0009829608)
These have been replaced with Brand New MB Batteries from Main Dealer Parts.

• I now have the following hard fault codes (*Please ignore - PA06DAA - aware of this issue*) that all seem to link to the Rear End Braking and Traction.
I have no idea what caused this and would like some help if possible.

The car drives - but the EML is now triggered causing the vehicle to drive in Limp Mode due to
C003700
State: Current
The Left Rear Wheel Speed Sensor Has a Malfunction.


Please see the following from the OBD Diagnostics:

1) Diagnostics Shows:
ECM - Engine Control Module (MED40) for Combustion Engine ‘M270’ (N3/10)
[FAULT: 2]

PA06DAA
State: Current
The actuation of the Valve of the Oil pump in the combustion engine has an electrical fault or open circuit

C003700
State: Current
The Left Rear Wheel Speed Sensor Has a Malfunction

TCM - Transmission Control Moduke (CGSFDKG (N15/13))
[FAULT: 1]
D40B00
State: Historic
An implausible Left Rear Wheel Speed Signal was Received

EPB - Electric Parking Brake
[FAULT: 1]
U012100
State: Current and Historic
Communication with ESP Has a Malfunction

ESP - Electronic Stability Program (N3 0/4)
[FAULT: 1]
U041586
State: Current and Historic
Implausible Data we’re received from control unit “Traction System”. There is an incorrect signal

SG - AWF - Control Unit ‘Distance’ Warning Function (A90)
[FAULT: 1]
C326600
State: Historic
Chassis CAN Bus: CAN Signal “Operating Condition” From Control Unit “Electric Stability Program” is Implausible.

2) Dashboard shows: See images attached


IMG_7660.heic
IMG_7661.heic
IMG_7662.heic


I really hope someone can help, as I’m stranded without a vehicle to drive. I’ve seen a video on YouTube


https://m.youtube.com/watch?v=zNW3YQhwpK4

Not sure if this is the same fix though.

• I have only changed the batteries thus far.
• there is a lot of brake dust/ soot and debris all over the rear breaking system (Alloys, Pads and Callipers may take off both wheels, and clean the area; and remove the sensor contacts and clean to see if this helps.
• Also considering ordering new speed and ABS sensors

All suggestions welcome.

Thank you so much!

moved to W246 forum...

When you allow the batteries to die, all the modules they support go haywire. Even a small drop in voltage can cause some of the codes you've got.

Is the charging system up to scratch? Min 12.0v engine off and 13.7v engine on. If not, you still have a problem with the charging and/or battery system. Sorry If im telling you what you already know.

Check batteries again. Clear.codes. ABS sensors are problematic in that they fail AND they are very sensitive to a fluctuation in voltage. Use quality parts there as cheapo ones have shown to be a problem.

All your codes are voltage and communication related which typically points to low voltage. What scan tool do you have? It is MB specific? You'll struggle to clear codes of it isn't.

Have you executed more than a single scan and fault code clearing? When I replaced my battery a year ago, it took 3 iterations to clear everything. Not sure if that was a consequence of my scanner's limitation or if fault codes are layered.

Agree with this. Also, the best way to change the battery is once you've done it, let ot sit with the Ignition on for 15 minutes before starting. It wakes up all the modules and allows them to power up before the starter, which can draw 100amps, temporarily drains the battery. Only works if your battery is fully charged.

And buy a battery maintainer to keep your batteries charged. Noco makes a 1 amp charger ($30) -- use it every time you'll be leaving your car parked for more than 10 days.