What are hall sensors?
Thread Starter
Member
Joined: Aug 2025
Posts: 104
Likes: 20
From: Texas
2015 ML350, 2020 BMW X7, 2005 LS430
What are hall sensors?
Dealer installed new hall sensors in the receipt they gave, not sure what hall sensors are? Also they applied a "mbclub" code which made the cost free, like $250 free. What are hall sensors supposed to do, couldn't find much online?
MBWorld Fanatic!
Joined: Jan 2016
Posts: 2,749
Likes: 881
From: In the Shadow of the Tetons
2013 ML350 Bluetec
They can measure rotation. PIcture a disk with magnetic bits at specified intervals on the edge - there could be any number of them, but let's put 360 there so there's one magnet every degree of rotation. The hall sensor is set close to those magnets so it can detect each time a magnet passes by. Using those detections, it sends that input to a computer that can calculate how fast something is rotating (a wheel, for example) or how many turns it has made or how many degrees it has shifted.
They're a part of an ABS brake system; using hall sensors the car knows how fast each wheel is turning. That info can also be sent to a speedometer.
PS: Your google fu needs work...
https://www.google.com/search?q=what...hrome&ie=UTF-8
They're a part of an ABS brake system; using hall sensors the car knows how fast each wheel is turning. That info can also be sent to a speedometer.
PS: Your google fu needs work...
https://www.google.com/search?q=what...hrome&ie=UTF-8
Last edited by rapidoxidation; Oct 7, 2025 at 05:18 PM.
Thread Starter
Member
Joined: Aug 2025
Posts: 104
Likes: 20
From: Texas
2015 ML350, 2020 BMW X7, 2005 LS430
So they have nothing to do with the camshaft sensors right? I think I asked dealer to take a look and inspect for any oil regarding the camshaft sensors but they did hall sensors instead for free. Interesting.
MBWorld Fanatic!
Joined: Jan 2016
Posts: 2,749
Likes: 881
From: In the Shadow of the Tetons
2013 ML350 Bluetec
Well, cams rotate... A hall sensor would help the ECM know what position the cam shaft is at...
I'm not 100% sure of the answer and maybe someone with more direct knowledge than I have will respond, but I would imagine a hall sensor is a large part of the camshaft sensor. Magnets on the camshaft end (a tone ring), a hall sensor to generate a signal from the tone ring.
https://www.google.com/search?q=do+c...hrome&ie=UTF-8
I'm not 100% sure of the answer and maybe someone with more direct knowledge than I have will respond, but I would imagine a hall sensor is a large part of the camshaft sensor. Magnets on the camshaft end (a tone ring), a hall sensor to generate a signal from the tone ring.
https://www.google.com/search?q=do+c...hrome&ie=UTF-8
Member
Joined: Jun 2025
Posts: 163
Likes: 57
From: Australia
2014 ML63, 2018 GLC43, 1929 DB victory six sports roadster
They could well be calling the cam sensors , Hall sensors.
The cam sensors pick up a signal from the reluctor wheel that is pressed onto the front of the Cam shaft. The reluctor wheel has gaps in it that the sensor pics up on. The sensor pics up on the metal section of the wheel.
The cam sensors pick up a signal from the reluctor wheel that is pressed onto the front of the Cam shaft. The reluctor wheel has gaps in it that the sensor pics up on. The sensor pics up on the metal section of the wheel.
Member
Joined: Oct 2023
Posts: 117
Likes: 45
From: Buchanan, SK CANADA
2013 ML350 Bluetec
"Hall sensor" is just a generic term for anything that detects a rotating magnetic field. I've never heard anyone refer to any sensor on any vehicle as a hall sensor. There's plenty of hall sensors on every modern vehicle but they have more precise names. I'm not saying the mechanic who called something a hall sensor was just trying to sound important but some might go there.
Trending Topics
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
MBWorld Fanatic!
Joined: May 2021
Posts: 2,524
Likes: 2,041
From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
That is the camshaft position sensor https://mbparts.mbusa.com/oem-parts/...rta0xF0-JKRzL4
