2015 C300

hello, long time owner of c300. Enjoying this car but this this error came few times and vehicle was running fine. Similar error came 3 months back and changing battery fixed it. But it came arain now. Few days back it stopped in the middle of traffic and started moving slowly. towed to local mechanic. Mechanic kept it for 2 -3 days and he says the error disappeared now and it is driving as usual and he cannot do anything else and asked me to take car. I am worried whether anything fixed automatically or the issue still there.
anyone faced similar problem? Any permanent fix? I don’t want my wife or daughter who uses them regularly stranded in the middle of the road.

 

Do you have access to an OBD scanner, or are you closeby an auto store that can do a scan for you?

 

it’s at the shop now. I am sure they might have scanned it. I can ask them to share the details. What is that I need to looks for or ask for ?

 

Ask for a printed copy of the scan results.

 

Attached are the diagnostic report. Technician says drive for another few days bring it back to check again. But he tells it’s a mystery.

any help and guidance is much appreciated.

 

I'd focus on the throttle valve actuator and the first group of 4. I assume your mechanic cleared the codes so that the problem will re-trigger the faults when they occur (?). Did he do any further diagnostics on the throttle valve?

 

yes. He cleared the codes and asked me to come back. He kept saying it could be idles problem. Is it related to the throttle valve actuator?

the mechanic seems to have experience with the European cars. He explained that it could be one of the electronics components but checking each one is not practically possible.

what I don’t understand is if the warning comes back again what are the chances are it tells the right code? That is what he is expecting I think.

regarding throttle valve actuator is it something DIY? I fed the report to Gemini and it spit out some options. I can do DIY to some extent. But not much on the cars.

 

Consider the meaning of the entire fault collection...both stored and current.

What stands out is the ECU being at the heart of this mess restricted on CAN-C only!
ISM + ESP are only on the receiving end.


this TRANSIENT acted as the root for this em'cy

This is a voltage transient that freaked out the ECU throttle circuit watchdogs. That is usually either a poor battery voltage or painted "GND post" circuits.


> Practical DIY Suggestions...

1. Clean ECU GND circuits sources!
2. Don't let batteries drain (use a CTEK float)
3. Defective throttle sensor (recalled TSB)
4. (ECU capacitor may be marginal)

Let's see where this repair goes...

 

You might want to find a shop that specializes in MBs. Try benzshops.com -- a mechanic with a MB Star Diagnostic System should be able to isolate the fault.

 

This is definitely a usual repair for MB Specialist only.
Neither Xentry or scanner can diagnose necessary steps to fix. A human brain understanding us required.

MB expertise will limit replacing too many good parts without improvements.

Nothing's wrong with throttle body part or adaptation.

 

Hi, I'm likewise still enjoying my '15 C300, so would appreciate more detail around your comment "it stopped in the middle of traffic" -- were you at a full stop while in traffic, or in motion and the car stopped suddenly, and if in motion, at roughly what speed? Thanks, and also I agree with earlier comments that an MB-trained tech would likely give you best guidance at this point. Cheers

 

How do you find in my area 30024 who has a correct scanner? Everyone charges diagnostic fee. I am checking benzshops.com but it just shows who are all around my area. But nothing about scanner.

 

My son was driving. But it was on a slower speed. it was on bumper to bumper traffic and it stopped accelerating and went to safety mode. So it would move like 2-5 miles speed.

 

Ya gotta love it -- "safety mode" -- this is when your car becomes disabled in the middle of an expressway where everyone else is traveling bumper to bumper at 80mph.

 

You can trust the list of MB Specialists you find in your Zip-code have the tools to work on your Mercedes... scanner + on-line services included.

If you want to be specific inquire about the Xentry Mercedes professional tool.
The pro will use that tool... to troubleshoot and guess what is really causing your powertrain limp-modes - Then replace and code parts to your car.

 

So took the car to another shop who specializes in Mercedes. The technician scanned for the code and found a new code U016887. Here are the list of events:
3/11 - Vehicle went into limp mode with inoperable error (see attachment from main post). towed the car to mechanic
3/11 - Mechanic ran the scanner and found bunch of codes. See original thread attachments
3/12 - 3/15 Car started driving as normal. Mechanic reset the code and asked me to take car and bring it/tow to him if anything happens again.
3/16 - took it to mechanic found in benzshop.com. His canner reported a new code (stored) U016887 (new attachment to this reply)

. He said since this happened since its been reset by previous mechanic, this might be the real problem.

He quoted $18xx to replace the EIS with emulator. He said it involves taking the steering wheel out, replacing with emulator and installing the steering back.
Since it is not an active code and car runs just fine, what are my options?