LAZARU5

My EQS 450 4Matic SUV was in the shop in mid-August for the complimentary 20K mile service. MBUX version 316 was NOT upgraded as part of the service. However, several software updates were applied to various control units to clear fault codes: B186D2A, U011587, POCF766, U00AC00, and U100814. No explanation of the fault codes was included with the service.

For the first 10 months of ownership during which I clocked 20K miles, I would regularly receive error and warning messages including the dreaded Battery Malfunction and Do Not Tow messages. Fortunately, I was never stranded for more than five minutes. In the five weeks since the software updates were applied to clear the fault codes, I have not received a single warning message.

Does anyone know where to find an explanation of the fault codes? I suspect that the EQ EVs have different fault codes than the ICE vehicles in the MB product line.

JoeMa

I do not know the answer to your question but wanted to post that I received the dreaded Battery Malfunction and Do Not Tow message the other day when getting reading to back out of our garage. All I diid was turn the EQS off, waited a few minutes, pressed the Start button, and the message was gone. Needless to say, that was a dreadful message to see on my dash. You mention that the service department installed several software updates to various control units to clear fault codes. Do you know if these updates are available OTA or if they can only be installed by the service department? Thanks

LAZARU5

Your experience seeing the Battery Malfunction message just as you were starting up and then clearing it fairly easily mirrors mine. Our SUVs were both put into service is Southeast PA in October 2022 soon after the launch, so the VINs should fairly close. I seriously doubt if the control unit software updates are available OTA. In the last eleven months I received two OTA updates. One to enable additional OTA updates and another to improve windshield defrosting to increase camera availability. I also saw some map updates, but these are not recorded in the OTA history in the Mercedes me app.

LastOne

Just received the Do No Tow and have High-Voltage System checked and multiple other warnings for the second time in 2 months. The car was in the shop for over 2 weeks after the fist incident. They tore the car down and did multiple software updates but suspect nothing was found.

Another posting suggested that the car does a reset after it is turned off and errors occur if that process is interrupted, possibly by turning the car back on or opening the tailgate. The recommended fix is to unlock/lock the car three time and walk away for 20 minutes (jumping on one foot and spinning around may also work if you have a fairy godmother). The recommended fix worked for me, but knowing workarounds should not be part of the Mervedes-Benz ownership process.

ope2k4

This is likely a battery pack issue. I’ve been stranded for hours as well and couldn’t get my SUV to start. North Houston MB shop manager told me they are required to try software patches, run the vehicle and see if the error codes return. They will order new battery pack for the vehicle if software patch fails in which case my did. My SUV is 2nd in line for the battery order and fix. I would recommend taking it back to the dealer to check the error codes for yours has returned.

Side note: My suv also had the risky drive shutdown which happens while driving. This never got resolved via software updates which I think is tied to the battery issue. I’m sure MB have the data for the cars they’ve done battery replacements on and hope this is not wide spread.

Battery replacement will be under warranty. They currently don’t have a way to change individual battery modules so the whole Battery drive chain is replaced. I was told it costs 90k$ which is nuts.

LAZARU5

What do you base this conclusion on? I am now up to eight weeks without any warning messages. I am even more comfortable with the reliability of the EQS SUV than I was when I started this thread. I do agree that $90K is an outrageous price for the battery module. They might as well just scrap the car and give you a new one.

Crito

Maybe it's the battery management system software since that would also explain the 12V issue some people are having. I haven't had any of these major issues with my EQE SUV anyways. It probably left the factory with the updated software already installed.

Personally, though, I wouldn't want an update applied unless it specifically fixes an issue I'm having. I'm not volunteering to beta testing software for MB.

ope2k4

No resolution yet. The car is still at the dealership as of today. I will provide updates via this post when I get an update.

ope2k4

I agree with avoiding unnecessary updates but I’m afraid all EQS service are categorized as software updates on the control modules without any specific info provided. This is likely due to the car being new and EV with very limited certified technicians.

ope2k4

lemon law isn’t as strong in TX plus I’m not sure if software patches counts as repair fix attempts. I also really like my non Mercedes pattern grille.

My EQS

LAZARU5

Was the replacement battery installed?

LAZARU5

It's been 3 months and 5000+ miles since the software updates were applied. Haven't seen a Battery Malfunction error since the updates. Still have not found explanation of error codes for MB EVs.

ope2k4

So I have an update. My car was with the dealer for over one month. They were likely waiting on Mercedes technical. Cause of issues I was having was an electrical fault. P0CF311 and P0CF766 were the codes. Fixes were to replace the DC Control unit and update MBUX. So they drained coolant, replaced the DC control unit and performed bleeding routine for cooling circuit. The kicker is level 3 charging didn’t work after they did tests so they replaced the DC control unit again. I picked up my car on Friday and haven’t had any issues since but I’m a bit nervous on highway because of past vehicle malfunction events that shuts the car down which needs me to find a safe spot to pull over to restart the car.

I should also say that I’ve now realized that battery malfunction is similar to check engine light in other cars that’s just a default warning signal for all issues. This is likely why fixes vary depending on codes. I have no idea how t\he DC control unit affected ignition or starting and battery ‘disconnect’ issues while driving.


I will update this post regardless of any issues reoccurring.

LAZARU5

I noted that the P0CF766 fault code is one of the codes reported in my SUV as well. I did not have any hardware replaced. Fault codes were cleared with updates of the software for control units. I am still running the 316 MBUX version. To which version were you upgraded?

While the Battery Malfunction may behave like a check engine light, I am not convinced this is intentional. I would not be surprised if this warning appears when a suitable warning message does not exist for a particular error condition not anticipated by the software engineers.

ope2k4

Info screen says RL_NTG7_E330.602_23063AC3. I’m assuming this the version number is the 330?