E220 Estate Rear Air Suspension
Thread Starter
Newbie
Joined: May 2026
Posts: 3
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From: Bristol, UK
2016MY, S212, E220 Bluetec Night Edition
E220 Estate Rear Air Suspension
Howdy folks, newbie here 
The rear air suspension on my 2016 E220 Estate wagon has dropped on both sides. This is not the first time it has happened - in December 2024 I had to replace the compressor - but generally it doesn't give problems. The car has normal spring suspension on the front.
This time the compressor is working just fine (if I link the high power contacts together) but the relay mounted behind the trim in the boot area isn't getting any voltage to energise the relay coil. With the compressor running, I have tested that air is passing through the valve block to the hoses/pipesthat go to the air bags but the suspension isn't rising so I'm a bit confused
I'm damned if I can find the wiring diagram or block functional diagram I used in 2024 to diagnose that problem so wondered if anyone can provide one, or a link to an on-line source?
Any assistance will be much appreciated
EDIT TO ADD: The VIN number is WDD2122012B326212 - it has code 677 for "Avantgarde/Standard Suspension" (whatever that means)
The rear air suspension on my 2016 E220 Estate wagon has dropped on both sides. This is not the first time it has happened - in December 2024 I had to replace the compressor - but generally it doesn't give problems. The car has normal spring suspension on the front.
This time the compressor is working just fine (if I link the high power contacts together) but the relay mounted behind the trim in the boot area isn't getting any voltage to energise the relay coil. With the compressor running, I have tested that air is passing through the valve block to the hoses/pipesthat go to the air bags but the suspension isn't rising so I'm a bit confused
I'm damned if I can find the wiring diagram or block functional diagram I used in 2024 to diagnose that problem so wondered if anyone can provide one, or a link to an on-line source?
Any assistance will be much appreciated
EDIT TO ADD: The VIN number is WDD2122012B326212 - it has code 677 for "Avantgarde/Standard Suspension" (whatever that means)
Last edited by Bristolian; May 4, 2026 at 08:32 AM. Reason: Adding information
Thread Starter
Newbie
Joined: May 2026
Posts: 3
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From: Bristol, UK
2016MY, S212, E220 Bluetec Night Edition
Thanks for your response. I think (hope) you're right but the only single point of failure is the valve block or the pipe that runs from the compressor to the valve block and, as far as I can tell, they're both good.
As the power relay for the compressor isn't being activated I am wondering if there is an electrical gremlin at play, hence my desire to have a block schematic and/or a wiring diagram.
As the power relay for the compressor isn't being activated I am wondering if there is an electrical gremlin at play, hence my desire to have a block schematic and/or a wiring diagram.
MBWorld Fanatic!
Joined: Aug 2021
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1983 Nissan Shltbox
If you bypassed everything and dumped air into the bags and nothing happened then you have a leak.
If the level sensor is whack then the relay may not be getting signal as the sensor data goes through a bunch of computers and stuff before it energizes the relay.
If the level sensor is whack then the relay may not be getting signal as the sensor data goes through a bunch of computers and stuff before it energizes the relay.
Thread Starter
Newbie
Joined: May 2026
Posts: 3
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From: Bristol, UK
2016MY, S212, E220 Bluetec Night Edition
@Senecat - Yeah, the fact that there are other modules involved is the exact reason why I'm trying to get a hold of the diagrams. You can't fault find something like this without them and my copy of WIS doesn't include the suspension system on my wagon which is coil springs on the front axle with air bags on the rear axle.
I've not yet dumped air straight into the bags - I'm waiting for a couple of Schrader valve-to-4mm pipe adaptors to arrive on Wednesday so I can do that. If the bags then take and hold air I can get more adventurous with my fault finding as I'll be able to get the car onto a level surface and put it up on axle stands - it's currently on ramps at the rear. I have no reason to believe that both level sensors failed at exactly the same time - it feels too unlikely - which leads me to suspect there is another single point of failure aside from the valve block (which appears to be functioning correctly). This elusive single point of failure could be something in the electronics or the wiring that's stopping the power relay from being energised. Of course, it is possible (if not probable) that the height sensors have been damaged by the collapse of the suspension and this is adding to the complexity of the issue.
I've not yet dumped air straight into the bags - I'm waiting for a couple of Schrader valve-to-4mm pipe adaptors to arrive on Wednesday so I can do that. If the bags then take and hold air I can get more adventurous with my fault finding as I'll be able to get the car onto a level surface and put it up on axle stands - it's currently on ramps at the rear. I have no reason to believe that both level sensors failed at exactly the same time - it feels too unlikely - which leads me to suspect there is another single point of failure aside from the valve block (which appears to be functioning correctly). This elusive single point of failure could be something in the electronics or the wiring that's stopping the power relay from being energised. Of course, it is possible (if not probable) that the height sensors have been damaged by the collapse of the suspension and this is adding to the complexity of the issue.
MBWorld Fanatic!
Joined: Aug 2021
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1983 Nissan Shltbox
What you previously described implied you already tried filling the bags. What I previously mentioned points that out. If you haven't ruled out the easy thing already (air leak) then you didn't explain yourself properly.
"With the compressor running, I have tested that air is passing through the valve block to the hoses/pipesthat go to the air bags but the suspension isn't rising so I'm a bit confused"
I'm not sure how else to interpret the above statement.
An air leak in the scenario you describe is most probable. In the case of the more anomalous electronics failure (barring any previous human intervention being a potential cause), you'll need the appropriate diagnostic equipment. Speculation diagnostics is not appropriate for a Mercedes Benz.
"With the compressor running, I have tested that air is passing through the valve block to the hoses/pipesthat go to the air bags but the suspension isn't rising so I'm a bit confused
"I'm not sure how else to interpret the above statement.
An air leak in the scenario you describe is most probable. In the case of the more anomalous electronics failure (barring any previous human intervention being a potential cause), you'll need the appropriate diagnostic equipment. Speculation diagnostics is not appropriate for a Mercedes Benz.
