Strange Electrical Gremlins - Head Scratcher!!
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2014 S Class Long
Strange Electrical Gremlins - Head Scratcher!!
First time poster, been scouring the forums but haven’t found anything!
I’m getting all of the faults on this inspection sheet.
they happen every time I drive more than like 15 miles, and they keep coming back. It started with just a multi-contour seat issue. Mechanic reset codes, seat features came back, great. No codes for a few days. Then I started the car and got a “Pre-Safe Inoperable” message. Took it to the mechanic, they found a few other codes, and they replaced my battery. Things seemed ok for the first 2 drives. Then boom - even more gremlins than before. To add to that, I hear this weird pump sounding noise - but not consistently. Only after the engine warms up. Tested AIRMATIC, and all the struts are good with no leaks. But the sound is so annoying and inconsistent. At first I though seat pump - but that works just fine and I can hear the inflate and deflate, alongside the other noise when it’s happening.
Now I get all these codes, with new ones popping up every so often. MB dealer isn’t sure without playing “whack a mole” with parts - and out of warranty that could get very expensive.
Only 20,000 miles, and I live in a rodent free area in Hawaii. Wiring looks good. I tested grounds in the trunk, engine bay, and under the seat. All good. I should also mention the other day I showed 64 miles of range, and 20% fuel. I stalled and my tank was empty somehow…
I’m at a loss!
I’m getting all of the faults on this inspection sheet.
they happen every time I drive more than like 15 miles, and they keep coming back. It started with just a multi-contour seat issue. Mechanic reset codes, seat features came back, great. No codes for a few days. Then I started the car and got a “Pre-Safe Inoperable” message. Took it to the mechanic, they found a few other codes, and they replaced my battery. Things seemed ok for the first 2 drives. Then boom - even more gremlins than before. To add to that, I hear this weird pump sounding noise - but not consistently. Only after the engine warms up. Tested AIRMATIC, and all the struts are good with no leaks. But the sound is so annoying and inconsistent. At first I though seat pump - but that works just fine and I can hear the inflate and deflate, alongside the other noise when it’s happening.
Now I get all these codes, with new ones popping up every so often. MB dealer isn’t sure without playing “whack a mole” with parts - and out of warranty that could get very expensive.
Only 20,000 miles, and I live in a rodent free area in Hawaii. Wiring looks good. I tested grounds in the trunk, engine bay, and under the seat. All good. I should also mention the other day I showed 64 miles of range, and 20% fuel. I stalled and my tank was empty somehow…
I’m at a loss!
Last edited by kalob.j.poen; Feb 6, 2026 at 12:04 AM.
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2014 S Class Long
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Joined: Nov 2016
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From: NYC
S63, GLE580, BV250
Considering the batteries are good. I would look next at the front and rear sam. Feel and look around for water intrusion into the interior and possibly getting into the module. When you locate the modules, check that all of the connections are clean and firmly fitted.
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From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
I wouldn't do anything without changing the Aux battery first. Sometimes batteries can test as good but still be faulty.
When you say the problems happen after driving the car for 15+ minutes, is it highway or stop and go driving? I assume stop and go because of your location, but thought to ask. Your Aux battery charges during stop and go, but not so much on highway drives. That fact might punch a hole in my aux battery guess.
When you say the problems happen after driving the car for 15+ minutes, is it highway or stop and go driving? I assume stop and go because of your location, but thought to ask. Your Aux battery charges during stop and go, but not so much on highway drives. That fact might punch a hole in my aux battery guess.
Thread Starter
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Joined: Feb 2026
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2014 S Class Long
Considering the batteries are good. I would look next at the front and rear sam. Feel and look around for water intrusion into the interior and possibly getting into the module. When you locate the modules, check that all of the connections are clean and firmly fitted.
No changes. But now the codes I’m getting are:U116787 Current | Stored Communication With The Left Front Reversible Emergency Tensioning Retractor Has A Malfunction. The
Message Is Missing.
Audio - Audio or COMAND
DTC Status Definition
B15BA00 Stored Communication Between The Media Interface And The Connected Device Is Defective Due To Faulty
Authentication.
B15B600 Stored Communication Between The Media Interface And The Connected Device Is Defective Due To Faulty Data.
B15B700 Stored Communication Between The Media Interface And The Connected Device Is Defective Due To Unknown
Data.
B15AC00 Stored SG-SW-L - Left Headlamp
An Unsupported Device Was Detected At The Media Interface.
DTC Status Definition
B1FB501 Current | Stored Temperature Sensor 5 Of Control Unit 'Headlamp Range Adjustment' Has A Malfunction. There Is A General
Electrical Fault.
B285913 Current | Stored The Output For The Side Marker Lamp Has A Malfunction. There Is An Open Circuit.
B286113 Current | Stored The Output For The Infrared Light Has A Malfunction. There Is An Open Circuit.
ESA 'Driver' - Electric Seat Adjustment 'Driver'
DTC Status Definition
B1EAF97 Current | Stored Easy Entry/Exit Has A Malfunction. The System Function Is Restricted.
AAC - Air Conditioning
DTC Status Definition
B218115 Stored The Power Supply For LIN Bus 1 Has A Malfunction. There Is A Short Circuit To Positive Or An Open Circuit.
B11BD07 Current | Stored The Actuator Motor For Air Flap 'Right A-Pillar' Has A Malfunction. There Is A Mechanical Fault.PARK - Parking System
DTC Status Definition
B125809 Current | Stored The Center Right Front Distance Sensor Has A Malfunction. There Is A Component Fault.
NSA - Night View Assist
DTC Status Definition
B1FFE00 Stored The Infrared Lamps Or The Low Beams Could Not Be Switched On.
Dealer recommends pulling up passenger carpet and checking the LIN1 Bus passenger ground splice. SAME is in the photo, looks good to me… but I have little experience with German vehicles
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2014 S Class Long
I wouldn't do anything without changing the Aux battery first. Sometimes batteries can test as good but still be faulty.
When you say the problems happen after driving the car for 15+ minutes, is it highway or stop and go driving? I assume stop and go because of your location, but thought to ask. Your Aux battery charges during stop and go, but not so much on highway drives. That fact might punch a hole in my aux battery guess.
When you say the problems happen after driving the car for 15+ minutes, is it highway or stop and go driving? I assume stop and go because of your location, but thought to ask. Your Aux battery charges during stop and go, but not so much on highway drives. That fact might punch a hole in my aux battery guess.
And I get these faults whether I’m doing highway driving or city stop and go, doesn’t seem to matter much.
I checked SAM. Looks fine to me.
Dealer recommends the LIN- Bus ground splice in the passenger footwell area. Said they need to cut into the harness and remove the crimp, strip the wires, and then crimp solder again.
They also think the “pumping” noise I’m hearing is the vacuum pump not being able to get stable voltage so it’s coming online randomly.
sounds like a nightmare in labor costs but, I’m not confident in my ability to it!
Last edited by kalob.j.poen; Feb 7, 2026 at 12:12 AM.
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Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
misc faulty modules
First time poster, been scouring the forums but haven’t found anything!
I’m getting all of the faults on this inspection sheet.
they happen every time I drive more than like 15 miles, and they keep coming back. It started with just a multi-contour seat issue. Mechanic reset codes, seat features came back, great. No codes for a few days. Then I started the car and got a “Pre-Safe Inoperable” message. Took it to the mechanic, they found a few other codes, and they replaced my battery. Things seemed ok for the first 2 drives. Then boom - even more gremlins than before. To add to that, I hear this weird pump sounding noise - but not consistently. Only after the engine warms up. Tested AIRMATIC, and all the struts are good with no leaks. But the sound is so annoying and inconsistent. At first I though seat pump - but that works just fine and I can hear the inflate and deflate, alongside the other noise when it’s happening.
Now I get all these codes, with new ones popping up every so often. MB dealer isn’t sure without playing “whack a mole” with parts - and out of warranty that could get very expensive.
Only 20,000 miles, and I live in a rodent free area in Hawaii. Wiring looks good. I tested grounds in the trunk, engine bay, and under the seat. All good. I should also mention the other day I showed 64 miles of range, and 20% fuel. I stalled and my tank was empty somehow…
I’m at a loss!
I’m getting all of the faults on this inspection sheet.
they happen every time I drive more than like 15 miles, and they keep coming back. It started with just a multi-contour seat issue. Mechanic reset codes, seat features came back, great. No codes for a few days. Then I started the car and got a “Pre-Safe Inoperable” message. Took it to the mechanic, they found a few other codes, and they replaced my battery. Things seemed ok for the first 2 drives. Then boom - even more gremlins than before. To add to that, I hear this weird pump sounding noise - but not consistently. Only after the engine warms up. Tested AIRMATIC, and all the struts are good with no leaks. But the sound is so annoying and inconsistent. At first I though seat pump - but that works just fine and I can hear the inflate and deflate, alongside the other noise when it’s happening.
Now I get all these codes, with new ones popping up every so often. MB dealer isn’t sure without playing “whack a mole” with parts - and out of warranty that could get very expensive.
Only 20,000 miles, and I live in a rodent free area in Hawaii. Wiring looks good. I tested grounds in the trunk, engine bay, and under the seat. All good. I should also mention the other day I showed 64 miles of range, and 20% fuel. I stalled and my tank was empty somehow…
I’m at a loss!
Your set of faults really isn't too bad, closer to average.
Your specific set of faults are not necessary all linked to a single root cause because they are scattered across buses.
The two I'd go after are the headlights and the seat belt tensioner to begin with.
They may be genuine wear and tear with Hawaiian high humidity level.
Mercedes modules uses a type of solderless connections that get oxidized to become intermittent gremlins.
The way 15mn timeout seems involved makes me think "drain by driving" low voltage may be involved here.
Find the way to display your batter vitals while driving daytime. A combination of steering wheel keys let you setup IC cluster to read Amps + Volts.
If you can swing electronic solderiron this will prevent you from replacingany modules:
- Door modules: mirrors!
- AirCon controller,
- HVAC Flap actuators,
- Headlamp controller
- ...
It's strange your "rain sensor" has not joined this pool, new already?
Last edited by CaliBenzDriver; Feb 7, 2026 at 01:29 AM.
Thread Starter
Newbie
Joined: Feb 2026
Posts: 5
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2014 S Class Long
I read you report and your thread, both top to bottom.
Your set of faults really isn't too bad, closer to average.
Your specific set of faults are not necessary all linked to a single root cause because they are scattered across buses.
The two I'd go after are the headlights and the seat belt tensioner to begin with.
They may be genuine wear and tear with Hawaiian high humidity level.
Mercedes modules uses a type of solderless connections that get oxidized to become intermittent gremlins.
The way 15mn timeout seems involved makes me think "drain by driving" low voltage may be involved here.
Find the way to display your batter vitals while driving daytime. A combination of steering wheel keys let you setup IC cluster to read Amps + Volts.
If you can swing electronic solderiron this will prevent you from replacingany modules:
It's strange your "rain sensor" has not joined this pool, new already?
Your set of faults really isn't too bad, closer to average.
Your specific set of faults are not necessary all linked to a single root cause because they are scattered across buses.
The two I'd go after are the headlights and the seat belt tensioner to begin with.
They may be genuine wear and tear with Hawaiian high humidity level.
Mercedes modules uses a type of solderless connections that get oxidized to become intermittent gremlins.
The way 15mn timeout seems involved makes me think "drain by driving" low voltage may be involved here.
Find the way to display your batter vitals while driving daytime. A combination of steering wheel keys let you setup IC cluster to read Amps + Volts.
If you can swing electronic solderiron this will prevent you from replacingany modules:
- Door modules: mirrors!
- AirCon controller,
- HVAC Flap actuators,
- Headlamp controller
- ...
It's strange your "rain sensor" has not joined this pool, new already?
I’ve owned several German vehicles, but always in San Diego and garage kept, the most I’ve ever had to do was a transmission replacement.
This humidity and water acidity is a new beast!
I plan on pulling carpet this weekend and checking all of the ground splices and connections under the footwells. Will be a big job - but I’m determined not to pay a technician to diagnose me with 37 module replacements that aren’t the actual root cause before they check wiring harnesses or ground splices. I’m an electrical engineer by trade… but for aircraft and guidance systems with very rigid manuals and troubleshooting guides. Cars always seem to be a level of “complex” simplicity that makes me overdiagnose.
Will be soldering any corrosion soon and will provide an update! The car was sitting outside in all types of Hawaiian weather for 235 days while I was in the Mediterranean, so I feel I’m only starting to see the full force of what the elements have done to the electronics while not in my garage.
Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Thanks for the insight!
I’ve owned several German vehicles, but always in San Diego and garage kept, the most I’ve ever had to do was a transmission replacement.
This humidity and water acidity is a new beast!
I plan on pulling carpet this weekend and checking all of the ground splices and connections under the footwells. Will be a big job - but I’m determined not to pay a technician to diagnose me with 37 module replacements that aren’t the actual root cause before they check wiring harnesses or ground splices. I’m an electrical engineer by trade… but for aircraft and guidance systems with very rigid manuals and troubleshooting guides. Cars always seem to be a level of “complex” simplicity that makes me overdiagnose.
Will be soldering any corrosion soon and will provide an update! The car was sitting outside in all types of Hawaiian weather for 235 days while I was in the Mediterranean, so I feel I’m only starting to see the full force of what the elements have done to the electronics while not in my garage.
I’ve owned several German vehicles, but always in San Diego and garage kept, the most I’ve ever had to do was a transmission replacement.
This humidity and water acidity is a new beast!
I plan on pulling carpet this weekend and checking all of the ground splices and connections under the footwells. Will be a big job - but I’m determined not to pay a technician to diagnose me with 37 module replacements that aren’t the actual root cause before they check wiring harnesses or ground splices. I’m an electrical engineer by trade… but for aircraft and guidance systems with very rigid manuals and troubleshooting guides. Cars always seem to be a level of “complex” simplicity that makes me overdiagnose.
Will be soldering any corrosion soon and will provide an update! The car was sitting outside in all types of Hawaiian weather for 235 days while I was in the Mediterranean, so I feel I’m only starting to see the full force of what the elements have done to the electronics while not in my garage.
Well make progress on a smooth glide slope.
This CAN-Bus setup is not rocket gyroscopic tracking.
The No1 issue is has limited amount of exposed data to troubleshoot with... that where forum help comes in. No wet-finger parts canon... get yourself a WIS setup to access schematics.
See my signature for electronic fun. We'll make it run right.
