Hello everyone,

My 2013 C 300 has been pretty reliable for me, bought in 2022 and has about 234,000 kms on it now. I use it as a leave behind vehicle, which is to say it gets driven no more than once a week for less than 50km, sometimes it'll sit for a few weeks. I brought it home on the 17th of December and started it up for the first time yesterday, where we've had -20ºC temperatures for 48 hours now. The car was a little hard to start but cranked over, no issues on the dash when I went to put the car in drive. The brakes were stuck as they've been exposed to the snow and elements for 5 weeks, so I needed to gently accelerate to break them free. That's when the problems started. Almost immediately after the brakes broke free all these warnings popped up on the dash saying my ABS, traction, stability, and TPMS were inoperative. The brake hold function unsurprisingly didn't work either. I figured it might be due to the extreme cold and lack of driving, but didn't have enough time yesterday to drive it.

I got home after about 10 minutes of driving and connected the battery directly to a trickle charger set to 6A where it ran for a few hours before the unit said the battery was charged.

This morning the faults appeared as soon as I started the car, as shown in the photo above. I let the car warm up for about 15 minutes before I took it out on the road, where I drove around town and highway speeds for over 30 minutes. The check engine light came on shortly after I started driving, and my ECO light which is usually displaying yellow was not on at all. I will pull the CEL code this afternoon when I take it for a drive.

Aside from the battery being weak still, newly bought from M-B in summer of 2022, my only thoughts could be: Fuse, sensor.

Until today the car has been extremely good, but this has been the longest it's sat without being started. Any advice on what to look for would be greatly appreciated, would love to be able to fix it on my own before taking it to a shop and spending more than the car is ultimately worth. Thanks in advance!

 

Does the vehicle have an aux battery? Check that as well. I wonder if voltage were too low at some point and it reset or shutdown some of the systems.

 

I would scan for codes and write them all down/take photos of the screen. Erase the codes then drive around and rescan for codes and see what it current. No sense in guessing without seeing the codes.

 

Watch this video. If your battery got too low, the alternator is not designed to recharge it. What trickle charger are you using? I recommend CTEK because that is who makes the Mercedes-labeled chargers.

 

Very likely a low battery or failing one.

Disconnect all power, that will clear all the codes while you charge the battery up to full and then see what errors reappear.

If you get a ESP or BAS error with a full battery than the next step is to do a full scan and read out any of the wheel speed sensors. These have a nasty habit of failing after swapping batteries after a low voltage event for some reason or another..

 

ABS, traction, ESP, and I think hold function are all controlled by the ABS controller. I think that circuit is where you’re going to find the problem. Of course, start with a hot battery. Look at the codes you pull for a sensor. The brakes needing to be freed may point to ice that jarred a wheel sensor out of place or disconnected it. I have had dried mud dislocate front wheel sensors (more common than ice down here). Maybe also a broken reluctor ring, but not my first suspect on facelift models.

Tough conditions to do under car trouble diagnosis. Can you get out of the weather? You may be pulling wheels to get it fixed.

 

May I suggest that once you have checked the battery condition, before doing anything else, is that you simply make sure the tyre pressures are all correct and then re-calibrate the TPMS (Tyre Pressure Monitoring System) - see your owners manual.