Airmatic Diagnosis
Thread Starter
Junior Member
Joined: Nov 2021
Posts: 66
Likes: 11
From: Texas
2017 E43 AMG, 2009 E63 AMG (fuel injector hydrolock, scrapped 2024), 1999 C230 Kompressor (sold)
Airmatic Diagnosis
Hi everyone,
I walked out to my 2017 E43 this morning when I saw the car was leaning down towards the back right tire. It wasn't slammed, but noticeably sagging. Anyway, I hit the unlock button on the key and the compressor came on for ~7 seconds and raised the back right. I did not observe if the back left was also sagging or not.
My question is: how can I diagnose the system? As far as I know, it could be the valve block, air bag, or air strut, correct?
I just purchased the car and had it inspected via my indie mechanic. He did not mention anything about the airmatic, so I assume the bags must not be dry-rotted or anything like that?
Any insight is greatly, greatly appreciated. I am worried.
I walked out to my 2017 E43 this morning when I saw the car was leaning down towards the back right tire. It wasn't slammed, but noticeably sagging. Anyway, I hit the unlock button on the key and the compressor came on for ~7 seconds and raised the back right. I did not observe if the back left was also sagging or not.
My question is: how can I diagnose the system? As far as I know, it could be the valve block, air bag, or air strut, correct?
I just purchased the car and had it inspected via my indie mechanic. He did not mention anything about the airmatic, so I assume the bags must not be dry-rotted or anything like that?
Any insight is greatly, greatly appreciated. I am worried.
Member
Joined: Feb 2021
Posts: 116
Likes: 38
From: Australia
W213 e300 MY19 (Aus market)
The air bag and strut is one unit. Generally simpler to swap out than separate coils and springs.
But you’ll need to diagnose whether it’s an air line leak, valve block failure or actual air bag leak.
Soapy water is one way to look out for it. Or this:
But you’ll need to diagnose whether it’s an air line leak, valve block failure or actual air bag leak.
Soapy water is one way to look out for it. Or this:
Last edited by aks_19_ak; Apr 23, 2025 at 05:50 AM.
Thread Starter
Junior Member
Joined: Nov 2021
Posts: 66
Likes: 11
From: Texas
2017 E43 AMG, 2009 E63 AMG (fuel injector hydrolock, scrapped 2024), 1999 C230 Kompressor (sold)
I really appreciate your response. I will take a look at the video in a little bit.
Regarding the bag/strut--I believe that's correct for the fronts, that they are one unit. But in the rear, they are separate, no?
If so, which unit generally holds the rear of the car up? I'd assume the bag itself but not sure. I've seen on YouTube that the struts generally last a significant while longer than the bags.
Anyway, I checked my car this morning (it should have been sitting for the same amount of time as last night) and the car was not sagging on any corner. I unlocked the car and Airmatic actually vented a corner rather than having the compressor come on. I will monitor for the next few days and replace the valve block soon. All of a sudden, I feel like a doctor.
Regarding the bag/strut--I believe that's correct for the fronts, that they are one unit. But in the rear, they are separate, no?
If so, which unit generally holds the rear of the car up? I'd assume the bag itself but not sure. I've seen on YouTube that the struts generally last a significant while longer than the bags.
Anyway, I checked my car this morning (it should have been sitting for the same amount of time as last night) and the car was not sagging on any corner. I unlocked the car and Airmatic actually vented a corner rather than having the compressor come on. I will monitor for the next few days and replace the valve block soon. All of a sudden, I feel like a doctor.
Thread Starter
Junior Member
Joined: Nov 2021
Posts: 66
Likes: 11
From: Texas
2017 E43 AMG, 2009 E63 AMG (fuel injector hydrolock, scrapped 2024), 1999 C230 Kompressor (sold)
That sounds nicer than having to purchase struts and bags for both sides ($1400 at least). Thank you, I really appreciate it. Interesting that the wagons have a one-piece system in the rear.
I'll update this thread or create another one for a valve block / airmatic filter (if the W213 has one...) replacement guide when I do so, my contribution to this forum.
Hopefully that's all my car needs... for now.
I'll update this thread or create another one for a valve block / airmatic filter (if the W213 has one...) replacement guide when I do so, my contribution to this forum.
Hopefully that's all my car needs... for now.
Member
Joined: Feb 2021
Posts: 116
Likes: 38
From: Australia
W213 e300 MY19 (Aus market)
Don’t take my word for it on the wagons. I may have confused the fact that some wagon versions have rear air suspension paired with standard coil springs in front, with the one piece vs 2 piece bag+strut shocks.
i did some YouTubing, and it appears that rears always have had a separate airbag aside the strut. From the look of things, if
yours is an air hose leak, the hose will be way cheaper but you will likely have to take more of the panels off to access and replace the air line.
i did some YouTubing, and it appears that rears always have had a separate airbag aside the strut. From the look of things, if
yours is an air hose leak, the hose will be way cheaper but you will likely have to take more of the panels off to access and replace the air line.
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Joined: Jun 2024
Posts: 191
Likes: 58
E320
Most likely what you’re seeing is early signs of either a slow leak at the rear air spring itself or a minor leak at the valve block that's letting that corner settle a bit after shutdown. On the W213 chassis rear setup, you’re right – the air spring is separate from the damper, so it's the bag that actually holds the ride height, and the strut just controls the motion. If it leaks down overnight but re-inflates immediately and stays up through driving, that's typical of a minor leak, not a total failure yet. Dry rot or tiny cracks near the folds of the bag are really common as they age even if they look "ok" on a lift inspection.
Since it’s not collapsing hard or immediately sagging every time, it’s still pretty early stage, but honestly without pulling codes from the Airmatic control unit and checking stored leveling faults, you're mostly guessing at whether it's a valve block or bag issue. Have you tried spraying soapy water around the rear bags and air fittings yet after shutdown to see if you catch any bubbles forming? That would be the first easy check I'd do before replacing parts.Here is a video that may help as weell.
Since it’s not collapsing hard or immediately sagging every time, it’s still pretty early stage, but honestly without pulling codes from the Airmatic control unit and checking stored leveling faults, you're mostly guessing at whether it's a valve block or bag issue. Have you tried spraying soapy water around the rear bags and air fittings yet after shutdown to see if you catch any bubbles forming? That would be the first easy check I'd do before replacing parts.Here is a video that may help as weell.
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Thread Starter
Junior Member
Joined: Nov 2021
Posts: 66
Likes: 11
From: Texas
2017 E43 AMG, 2009 E63 AMG (fuel injector hydrolock, scrapped 2024), 1999 C230 Kompressor (sold)
I appreciate y'all! The bag alone holding up the rear is exactly what I wanted to hear. I'm hoping for it to be a valve block replacement and I have what I hope is some evidence for it:
The car has not sagged since 4/22 despite sitting for ~ the same amount of time (the compressor has not come on with unlock from the key, and I crudely measured wheel-to-fender with my mini iPhone--nothing seems to be off except for occasional venting of a corner because it's too high, attributable to air temp/pressure changes?)
If there were a leak in the bag, it would leak down overnight, very consistently, correct? And the car adjusts Airmatic on the actual UNLOCK (when the door actuators do their thing etc...) with the key rather than sensing the key come up to the car?
Along with the valve block, does anybody know if the W213 has an Airmatic filter, and what the part number is? It's very hard to imagine the system is entirely unfiltered. I questioned FCPeuro via email, and checked EPC to no avail.
"Unfortunately, we don't seem to carry the Air Compressor Filter for your application. I wasn't even able to locate a part number for you. I'm very sorry."
The car has not sagged since 4/22 despite sitting for ~ the same amount of time (the compressor has not come on with unlock from the key, and I crudely measured wheel-to-fender with my mini iPhone--nothing seems to be off except for occasional venting of a corner because it's too high, attributable to air temp/pressure changes?)
If there were a leak in the bag, it would leak down overnight, very consistently, correct? And the car adjusts Airmatic on the actual UNLOCK (when the door actuators do their thing etc...) with the key rather than sensing the key come up to the car?
Along with the valve block, does anybody know if the W213 has an Airmatic filter, and what the part number is? It's very hard to imagine the system is entirely unfiltered. I questioned FCPeuro via email, and checked EPC to no avail.
"Unfortunately, we don't seem to carry the Air Compressor Filter for your application. I wasn't even able to locate a part number for you. I'm very sorry."
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"jimyj" is a sales pitch. Have a look at any 5 or so of jimyj past posts. You just might notice the artificially personalized robotic responses that, about 80% of the time, happen to mention a certain scanner ;-)
Thread Starter
Junior Member
Joined: Nov 2021
Posts: 66
Likes: 11
From: Texas
2017 E43 AMG, 2009 E63 AMG (fuel injector hydrolock, scrapped 2024), 1999 C230 Kompressor (sold)
Well he seems pretty helpful to me but I'm not falling for youcanic regardless.
Is there anybody who could help me locate a part number if/for an airmatic system filter for the w213? FCPeuro, ECS, and Arnott were unable to locate one for me. I checked through some version of EPC but am still unable to find the part.
I really don't want to disassemble my car before having the part in hand.
I also can't quite believe that the w213 doesn't have an airmatic filter at all, if it really doesn't. Perhaps the pump has a screen that has to be cleaned or something? No way MB would let dirty air and contaminants get into the system... right?
I just realized it may also sip filtered air from the cabin dust filter or engine air filters, pre-MAF. No idea how to verify that though.
Is there anybody who could help me locate a part number if/for an airmatic system filter for the w213? FCPeuro, ECS, and Arnott were unable to locate one for me. I checked through some version of EPC but am still unable to find the part.
I really don't want to disassemble my car before having the part in hand.
I also can't quite believe that the w213 doesn't have an airmatic filter at all, if it really doesn't. Perhaps the pump has a screen that has to be cleaned or something? No way MB would let dirty air and contaminants get into the system... right?
I just realized it may also sip filtered air from the cabin dust filter or engine air filters, pre-MAF. No idea how to verify that though.
