Airmatic Fault Code C1390

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Mrhanky

MB Enthusiast
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Jun 19, 2014
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1,599
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Superb 3.6 4x4 & W221 S500
Does anyone know what the airmatic fault code C1390 (5390) relates to or the description.

Has anyone had experience of this fault before? The car raises and lowers fine and shows no sign of any air being leaked. Also the fault appears straight away when the key turns so makes me think its electrical / sensor related but Im not sure.

I popped to MSL this morning and they pulled the above code. They cleared it and test drove the car and it did not return. However, sods law it reappeared on the drive home. I need to do some long journeys next week and wanted to have a look myself so any help is greatly appreciated.
 
Well 5390 refers to airmatic valve unit right rear suspension strut,you need to get a indy who knows what he is doing with the Star they can run tests on the airmatic suspension.
 
Well 5390 refers to airmatic valve unit right rear suspension strut,you need to get a indy who knows what he is doing with the Star they can run tests on the airmatic suspension.

I assume we are talking about the damper unit not the air bag?
 
Yes the fact that you can raise and lower the car should rule that out,I would get a indy to test the system,the Star diagnostics is a very powerful tool,I had a pump give out because there was a small air leak,the fault only came up every so often I took it to my indy and he tested the system the Star emptied the air tank and then the pump and so many seconds to fill it, 3 times out of 5 it failed because the pump had worn itself out because of the leak,i was impressed.
 
Thanks, yes I've had a pump fail about two years ago. I now replace the piston ring and relay on an annual basis.

Acid did me a favour squeezing me in this morning and I will take it back next week for a full diagnosis.

I hope it's not the dampers as they recently cost Alps a fortune to replace.
 
Talk to me more about the piston ring / relay replacement ??
 
Talk to me more about the piston ring / relay replacement ??

The piston ring on the pumps wear and then loose power, this then means the pump has to work harder and then fails.

The replacement o ring and piston ring costs about £15 and takes an hour to do.

The relays have been known to fail and keep the pumps on which makes them fail.
 
I am currently going through the expense of changing all four air springs on my car.
Just found the outer joint on the rear spring control arm is worn, unlike the steel arm the joint cannot be changed. So two new arms needed at £240 each if I want to be rid of the annoying clunk.
Let's hope it will be fit and forget.

Here is a link to the compressor O and piston ring:
https://x8r.co.uk/mercedes-e-class-...on-compressor-piston-ring-repair-fix-kit.html

Tony
 
Popped car to Msl this morning to get it looked at in more detail. Acid was great as normal and squeezed me in despite having staff off on holiday. The result is the rear shock has developed an electrical fault. Best price I can get is £410, I'm thinking as they are the original shocks and done 120k miles I should ideally replace both together.

Thanks to Alps the part number revision was easy to obtain and the job looks okay if I can be bothered to do it myself.
 
Oh boy where do I start?

Well, I decided to replace both dampers rather than one and the price was eyewatering, the AMG tax in full swing. They turned up yesterday and I had removed the old ones on Sunday so I was all ready to go.

Fitting was easy, again thanks to Alps for his excellent DIY. So after I had it all installed I jumped in the car and the very same error greets me, ahhhhhhhhhhhhhhhhhhhh.

Popped to MSL and Acid kindly cleared the code and I did a test drive. After a few mins the code reappeared. So looks like I changed the dampers for nothing, well that's not technically true as they had done 120k miles and one could argue they owed me very little.

The result now is that the rear damper / strut circuit still has an open error. So I guess its going to be an issue with the connector block or wiring post the connector that's the issue.

Does anyone have any experience of this / tips / pics of the wiring or an idea of how I get to the wiring behind the main connector block.
 
Does anyone know where the fuses for the airmatic are located?
 
Does anyone know where the fuses for the airmatic are located?

Drivers side, end of dashboard behind pull off panel. Its Fuse #37, 30amp, 6th one down in the row closest to the drivers seat.

Also another fuse located in engine compartment, drivers side Fuse #F45.
This fuse is the last fuse on the right (12th fuse) in the row closest to the drivers wing.

According to the copy of WIS I have printed off for my 2004 E55,

The relay S (Airmatic relay K67) is only clipped on at the driver-side SAM control unit with a fuse and relay module

If you want a copy of all the fuses and relays, along with their locations for a 2004 W211 E55, PM me with your address and I'll print off a copy and post to you (7 pages)
 
In the interests of keeping this thread upto date and the potential to help others with the similar problem I will update my findings.

On Wednesday I decided I needed a code reader that could read all the relevant modules. A bit of research revealed the icarsoft MB 2 as a reasonable choice.

I figured it was pointless testing things without being able to tell what codes where being thrown up. The mb2 turned up on Friday and a quick play, I was up and running.

I woke up this morning and thought right lets try and get to the bottom of this. So in between looking after my eight year old, I investigated the fault further.

So a few hours of testing and I have located the cause of the error. Firstly I can confirm that Y54 on the rear does not relate to the damping unit, rather its the airbag strut. 1y1 is the additional volume valve within the airbag strut. For information 1y2 is the level control valve also contained within the airbag strut.

Once I realised this I moved the wiring for the right rear strut and connected to the left rear airbag. Hey presto the fault now becomes Y53 (left rear strut) 1Y1 / 1Y2 open circuits. So the fault is in the rear right airbag itself and will need to be replaced.

I have a far better understanding of how the whole Airmatic works and what codes relate to which parts now.

Its an interesting fault as in 2012 my car had the Arnott airbag conversion kit fitted. I think they have a life time warranty so have fired off an email to Arnott but not holding out much hope as the words Limited appears a lot in their text.

So now wondering if the new version of the Arnott bags are compatible with my older version and if just replacing one is okay.

Im very glad to have diagnosed the issue and now just need to get around to rectifying the fault. I hope my pain and efforts assists others in the future.
 
Ordered a replacement air strut from HIDs direct. They are an official supplier and the unit turned up yesterday.

Comparing my old arnott unit to the revised version there is a big visual difference, although Arnott have reassured me they are compatible with each other.

Spent yesterday afternoon fitted the new unit. The fitting was not too bad but had to remove it all first time as one of the connector pins bent.

The car is now tip top. I may well change the other sides air strut next month just because I'm a nutter with things and need to know it's been done.
 
The piston ring on the pumps wear and then loose power, this then means the pump has to work harder and then fails.

The replacement o ring and piston ring costs about £15 and takes an hour to do.

The relays have been known to fail and keep the pumps on which makes them fail.

Is it an easy DIY ?

Bumper off job ?
 
Is it an easy DIY ?

Bumper off job ?

No need to remove bumper to get to pump. Jack left front of car up and secure with axle stand.

Remove wheel and arch liner, easy to do just some nylon 10mm nuts and some body fasteners.

Once removed you will see the pump sitting in the corner.
 
Although you do not need to remove the compressor from the car to change the piston ring, just be aware that the posts on the bracket that the pump hangs on are very thin and may snap when undoing the nuts to remove it.

The new bracket has thicker posts and will need new washers, collars etc.
The EPC shows the "superceded by" part number for the new bracket fine but neglects to point you in the right direction for the new part numbers for the larger washers and collars.

Apart from that, it is a quick and easy job.
Tony
 

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