C350e - S205 - Post Servicing Woes

[Eoforwic]

Good evening, everyone,

First post, for my spouses C350e (S205) 2015 Wagon .

Last Friday (17th May) - My spouse dropped off the car at a well known Mercedes Independent for an A2 service with no dash error messages. Service completed and was told that it needed rear brakes and pads, which were then completed the same day. When picking up the car, we noticed it had a dash light. Garage then re-scanned it and said it was the front near side ABS Sensor. Due to work commitments, we couldn't leave it so drove it home, during which the car was fine apart from ABS warnings etc.

Saturday (18th May) - Started the car and more warnings appeared, traction control and auto-assist etc, which we thought were all ABS sensor related. Drove a short distance and the car then said the electronic parking brake (handbrake) was inoperable (which we assume is/was linked to the brake service, pad placement) - this was combined with the power steering being much heavier, basic electronic systems, not working - like the rear camera, the turbo not kicking in and the speedo not working etc. We got to our destination and parked somewhere level, then later drove home (during which the hybrid system worked) and parked the car outside the house. Phoned the servicing garage and explained, who said drop it in, Monday.

Monday (20th May) - Went to the car and it was dead/battery flat. Keys wouldn't open it (electronically) and when I got into it, using the emergency key access, it had a completely flat battery. I got it started using a fresh unused battery from another car and the car had all the same errors as the Saturday, apart from it now also said, to stop driving to charge the 12v battery. Dropped it off at the garage and their initial diagnosis, is that it has had a hybrid battery overheat as one of the 30 codes (now including the ABS sensors on all 4 wheels) is the coolant valve on the hybrid system.

Question - Do the symptoms, support it being the hybrid system or would a bad 12v battery look the same, e.g. the different sensors reporting a fault when the system voltage was too low? Would a bad battery cause a fault by its self? Could it have a parasitic drain? Are there any common problems with post servicing the 350e, where is suddenly has 30 ish codes? Is there a common parasitic drain for the car - does the car having a fault, cause the computer to stay active, as I could see even after locking it on Saturday, that the hand brake warning dash comment was still active. What could this be apart from the hybrid system? Which would be the most expensive option and least preferable option - If the car wasn't a Hybrid and had all these symptoms, would you just change the 12v battery?.

 

[malcolm E53 AMG]

Welcome!

First thing I would do is renew the 12V battery a failing battery can throw up all kinds of electrical issues, if that doesn’t resolve the problem clear the fault codes and see what comes back and then deal with those faults

 

[JBell]

First thing to do is take it back to the garage, if you dropped it off with no faults and it had faults when you picked it up then something has happened and the garage need to sort IMO

 

[Eoforwic]

Spoke to the garage again today (21 May) a d they are going to fit a new 12v battery, reset all the codes and then see what the car does. I predict it will be fine, with a hand brake issue.

 

[mioba]

Let us know how you got on

 

[Eoforwic]

Spoiler alert! - The car is still broken.

I spoke to the garage on 21st, as described and they said they'd fit a battery the next day (22nd) . Anyhow with 4 unanswered calls., no one ringing me and looking at the app (The car tells me whether it has been unlocked etc), it was obvious that nothing had happened on the 22nd.

On the 23rd, the car says its been unlocked and has a very low battery, no surprise there! I ring about 2pm and ask for an update. The garage say, a new battery has been fitted, all codes reset and while on a test drive, the car went back into limp mode, but there are now less codes.

The codes they are focusing on as 'the issue' are the front ABS sensors (both now need doing) and thankfully, it doesn't seem like the hybrid system is at fault. They are also planning to update the traction control system.

Since, then I've not had an update. As of today, I can see the car has a very low 12v battery again and the parking brake isn't applied.

The only work they did on the car (during the service) was the rear disk and pads, so perhaps it is an electrical fault with the replacement wear sensors (being faulty) or if the pads aren't in the correct position, that can also cause a handbrake issue. The handbrake fault (it not being engaged) could then be causing the car to stay active and discharge the battery? When we had the car, and I pressed the parking brake button, I could feel the brake pedal depress, so it felt like it was working electro-mechanically but not binding.

My frustration, is that I'm having to chase them for updates and it feels like they are just code chasing rather than thinking about what could be wrong with the car to cause the codes, e.g. once the car had a fully charged 12v system, it got rid of most of the codes. If they change the ABS sensors and the ABS codes remain as faults, I'm not sure they will be able to think outside the box.

I understand, they are fitting it around their other work, however, the car was fine (it didn't have dash lights) when it went in and now has a handbrake issue, which is exactly the system they worked on. The other frustration, is they didn't explain before we paid circa £800 that the car now had codes, that it didn't have when we dropped it off. The garage are always on the back foot, and as a customer it is just disappointing that I'm having to learn about 350e's and write forums posts to get it fixed, when they are the subject matter experts.

My next steps will be asking by email for an update, setting a deadline and then I'm going to get the AA/RAC to do an inspection report so I can move this along. Thankfully, I have my personal car back now, so I'm not having a 4 hour commute a day by public transport while my spouse had my car for work.

 

[alexanderfoti]

From a tech perspective, I all your initial symptoms sound like a wheel speed sensor fault. Potentially something was dislodged when it was worked on etc.

Have you voiced your frustrations to the workshop directly? Imo, make it clear that your not happy and let them sort it.

 

[Uncle Benz]

From a tech perspective, I all your initial symptoms sound like a wheel speed sensor fault. Potentially something was dislodged when it was worked on etc.

Have you voiced your frustrations to the workshop directly? Imo, make it clear that your not happy and let them sort it.

To me too, but the handbrake faults when new discs/pads were fitted… did they rewind the calipers with Xentry, or at worst steering wheel buttons? That’s not a problem, but I’ve seen people take the motors off the calipers, rewind by hand and then put them back. That’s a recipe for disaster…

 

[alexanderfoti]

To me too, but the handbrake faults when new discs/pads were fitted… did they rewind the calipers with Xentry, or at worst steering wheel buttons? That’s not a problem, but I’ve seen people take the motors off the calipers, rewind by hand and then put them back. That’s a recipe for disaster…

Absolutely agree. I'd hope any merc specialist wouldn't so anything like that!

 

[Eoforwic]

Thank you for your points, today (28th) I have had no contact from the garage. I am going to email them.

 

[Eoforwic]

I picked up the car on Friday (31 May) and have now run it for a few days and seems fine. The issue was the two front ABS sensors failed, which then created an issue where the car computer/systems didn't go into sleep mode, which then discharged 12v battery, triggering several other spurious of codes/warnings.

From all my forum(s) research I did on this, when I got told it was the hybrid battery and therefore a write off (circa 10k to fix). Any issues with the W/S205 - make sure the main 12v battery is fully charged, before you then look to solve whatever is actually wrong. With the 350e, if you have a battery issue and it may be the hybrid issue, it is normally solved by a new 12v battery or a new 12v auxiliary battery (in the passenger footwell) or changing the starter motor. The car does not have an alternator, so don't go down that rabbit hole.

My feedback (constructive) about the garage is it wasn't great at communication on the issue, no update until it was fixed etc- however, the work they did was great and was really good value. Also looking at the garage, while a Merc specialist, they don't list EV/Hybrid as an area they specialise in, so I may take it to a specialist EV/Hybrid garage in the future to make sure the system, which if it did fail would write the car off and accept they don't know Mercs' as well.