Greg Buechler

Last Sunday we took our new 2023 C300 4Matic (1200 miles on the odo) out for a jaunt to a nearby winery. We stopped to refuel a few miles from home, and I happened to watch the attendant take care of that (I have to; I live in western Oregon). I heard the cap click against the stop. We proceeded to the winery about half an hour away using cruise control much of the way and parked facing the vines a few feet away. After about 45 minutes we got back into the car to go home, and I started it up. It stopped running immediately and I got a "Distance Control Inoperative" error message and a CEL. Perplexed, I tried to restart and got the same two indications and a "Do not start" as well. At that point I called M-B roadside assistance and ordered a tow to the dealership, knowing that I would have to restart again just to put the transmission into Neutral to load the car on a flatbed. It took nearly four hours to get a truck to the site. When I started the car to select Neutral, the CEL remained lit but the other indicators were not. We got the car to the dealership after hours so I had to use the key drop and the little form that never has enough space for a through description of the problem.

Mid-morning on Monday I got a call from the service advisor, who told me that he'd started the car that morning and drove around the lot and saw no error messages (!!! I see a Do Not Start message, note that, and the first thing he does is start the car!!!). He asked for a more detailed explanation of what occurred, which I gave to him just as I am describing it here. He said that he'd have a technician dig into the error codes to see what was stored and get back to me. Four days now, and crickets. Has anybody else had this happen? I'm inclined to think a sensor glitch started it, and the Do Not Start might have been triggered by me attempting to restart without giving the car time to reset itself. Any thoughts on what I should ask the service advisor next? I don't suspect the fuel filler cap; wouldn't that have triggered the CEL immediately following the refueling?

alexasa

iTrader: (1)

IMO, CEL = drive it till it literally breaks down on the side on the road. It used to mean something - nowadays it means nothing. Mostly electronic glitches or loose gas caps.

I have a fleet of sprinters and when a tech calls in with a cel - I just have them continue driving. I also had a CEL on my brand new W206 C43 AMG. Most of the time they go away after some period of time if the car is off.

It's simply not my problem if the car is under warranty - I can't be bothered to be inconvenienced like that.

Greg Buechler

Update: Just got the car back. It took some sleuthing over a few days, but the culprit was found: Two crushed pins on Connector 2 of a wiring loom going into the PTCU. This created the intermittent no-start condition and threw at least seven fault codes in the PTCU, ISA, VGS, and AMG-DRVU modules. The last one is particularly interesting since the C300 doesn't have the AMG Drive Unit option but whatever. They found no fault in the Distronic system but suspect that the error shown on the instrument panel was related to all the other fault codes; the crushed pins were causing communication errors all over the place. The problem originated at the factory. The pins have been replaced and the wiring loom rerouted to prevent a reoccurrence, so all is right with the car once again.

W205C43PFL

Strange it didn't happen during QA as you would think if the pins were crushed would had threw error codes the moment the vehicle was started long before you took possession of it?

W205C43PFL

I see so there wasn't any stored code right

W205C43PFL

OP did the SA requested images of the error messages and if so did you provide them?

Greg Buechler

That's the same though expressed by another friend of mine, and I agree that it is mystifying. According to the service advisor, these particular pins and the crosstalk errors they could generate would have continued to be intermittent and primarily affect the start sequence. Another weird thing is that errors were thrown in the AMG DRVU module, which must be the controller for the AMG Drive Unit. The C300 doesn't have that piece of kit as an option, so it is surprising that the car apparently has the controller embedded as part of the standard wiring harness. I suppose that someone with sufficient skills and the ability to properly code the car could purchase the rest of the required parts and retrofit that system to a C300. Despite having once been an autocrosser and the occasional track day participant, I'm not sure why you would really need or want the AMG Drive Unit on a garden-variety C300 4Matic.

Greg Buechler

No, the SA didn't request images. I didn't shoot any with my phone, but apparently there's a way to call them up out of storage by using the car's system menu. Yeah, I've read the manual a couple of times but that particular thing didn't really register. I must admit, that at 60 learning the ins and outs of a new car whose tech level is a full quarter century more advanced than my previous car is proving to be a challenge.

W205C43PFL

Yup the W206 has a lot more tech compared to competitors and even MB's previous generation, the W205.

W205C43PFL

I guess they included it as it simplifies the production process but just a guess.... sometimes the modules don't cost much for MB but having less versions of one thing actually helps saves cost but again just a guess.

I am still not convinced with your SA's explanation why it wasn't noticed after production but lets just hope that it is really fixed and no more issues down the road.

Greg Buechler

Agreed!

There were fault codes stored. Here's the list according to my service document: " Found numerous communication and drive authorization faults (each with only one occurrence): U025687, U016887 in PTCU; P143400 in ISA; P060600, P051300 in VGS, U01487, U011587 in AMG-DRVU. Inspected PTCU and found CAN wires at terminals 1 and 2 of connector 2 crushed. Repaired damaged wires and ensured proper harness routing. Cleared faults."
The technician found no faults with the Distronic but suspects the message was also due to the crushed wires causing communications issues and recommends that I monitor for further occurrences of the error message. Haven't had need to use cruise control yet after the repairs, so it might be a while before I can evaluate that.

W205C43PFL

Hopefully it fixed it completely!

W205C43PFL

...and stays fixed