C-Class (W204) 2008 - 2014: C180K, C200K, C230, C280, C300, C350, C200CDI, C220CDI, C320CDI

2012 C250 Melted ECU Relay

Old Jan 14, 2026 | 08:19 AM
  #1  
ryanholi0's Avatar
Thread Starter
Junior Member
Liked
Loved
 
Joined: Jul 2025
Posts: 31
Likes: 17
2x 2013 r231 SL550
2012 C250 Melted ECU Relay

What in the heck would cause this to my friend's 2012 C250?
A little background first. This car is beat to heck. First it needed a starter and new battery and then I changed out the alternator for her. But just before, she had damaged the front end in the drivers side and the Windshield washer sprayer came on and would not stop!
So I changed out the alternator, cleared all the codes. alet it run for a good hour with no problems. She comes and gets it, drives it to a store and then the ECU relay melted! What in the world! You could also hear some motor running right below the driver side headlight (assuming something to do with the windshield washer?
Any Ideas at all what would cause this to overload and melt?


Reply
Old Jan 14, 2026 | 08:52 PM
  #2  
cvx5832's Avatar
Super Member
15 Year Member
Liked
Loved
Community Favorite
 
Joined: Apr 2008
Posts: 764
Likes: 171
From: Walnut Creek, CA
325Ci, 325Cic, C300
Cheap Chinese alternator?
Reply
Old Jan 14, 2026 | 11:51 PM
  #3  
Odd Piggy's Avatar
MBWorld Fanatic!
10 Year Member
Liked
Loved
Community Favorite
 
Joined: Sep 2013
Posts: 2,346
Likes: 692
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
I’m guessing something related to the front end damage throwing a big load across circuit 87 that shouldn’t be there. But it could be anything. Why it didn’t blow a fuse in the pre-fuse block is outside my experience. It looks like that fuse block may now be history. If the car is a beater, maybe the whole car.
Reply

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 

Thread Tools
Search this Thread
Rate This Thread
Rate This Thread:
You have already rated this thread Rating: Thread Rating: 0 votes,  average.


All times are GMT -4. The time now is 05:00 AM.

story-0
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

Slideshow: Not every Mercedes design becomes timeless, some feel stuck in the era they came from.

By Verdad Gallardo | 2026-05-12 18:09:07


VIEW MORE
story-1
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

Slideshow: Yes, Mercedes built manual cars, and some of them are far more interesting than you'd expect.

By Verdad Gallardo | 2026-05-02 12:36:58


VIEW MORE
story-2
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.

By Verdad Gallardo | 2026-04-29 11:19:28


VIEW MORE
story-3
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

Slideshow: Before curves took over, Mercedes mastered the art of the straight line, and some of those shapes still look right today.

By Verdad Gallardo | 2026-04-25 12:05:49


VIEW MORE
story-4
Flawlessly Restored Mercedes 190E Evo II Heads to Auction

Slideshow: The 190E Evolution II shows how a homologation necessity became a six-figure collector icon.

By Verdad Gallardo | 2026-04-22 17:53:47


VIEW MORE
story-5
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

Slideshow: Mercedes is turning one of its core nameplates electric, and the details show just how serious this shift is.

By Verdad Gallardo | 2026-04-21 13:58:06


VIEW MORE
story-6
Mercedes EQS Gets A Major Update: Everything You Need to Know

Slideshow: Faster charging, longer range, and a controversial steer-by-wire system define the latest evolution of Mercedes-Benz EQS.

By Verdad Gallardo | 2026-04-15 10:35:34


VIEW MORE
story-7
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

Slideshow: These overlooked Mercedes-Benz models never got the spotlight, but they quietly delivered more than most remember.

By Verdad Gallardo | 2026-04-13 19:35:45


VIEW MORE
story-8
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping

Slideshow: A well-used 1991 Mercedes-Benz 300D with more than one million miles is now looking for a new owner, and it still appears ready for more.

By Verdad Gallardo | 2026-04-10 10:05:15


VIEW MORE
story-9
10 Most Reliable Mercedes-Benz Models You Can Buy Used

Slideshow: From bulletproof sedans to surprisingly tough SUVs, these Mercedes models proved that the three-pointed star can go the distance.

By Verdad Gallardo | 2026-04-08 09:55:49


VIEW MORE