D3 Air suspension problem

AAgh.
Chasing faults on this D3 of a friends.
2008 model 2.7
Various problems initially, including EAS compressor problem
So it's had a new AMK compressor, and had its programming updated as it was the later type compressor. The pipe work to the filter was damaged so have replaced that.
So it goes up and down OK, drives nicely, but after about 3 miles the orange warning comes on and a message on the dash saying suspension fault.
It brings a code C1A20 - pressure increases too slowly when filling reservoir - intermittent
No obvious leaks anywhere.
Can anyone give me any pointers please?
Thanks
Just to add, it doesn't sink overnight,

Garys your man and I bet he will answer this pdq

If the old compressor was failing there's a chance the pipe from compressor to the air reservoir is blocked with silica or even reservoir itself can have a pin prick on them, generally on top of them, if it's the original reservoir it's probably worth replacing anyway

Have a look through these pages
https://disco3.co.uk/gallery/albums...s_and_Testing_Vehicle_Dynamic_Suspension_.pdf

@gstuart will know....

hi

unfortunately there can be multiple faults that can cause this

to ensure the following it’s a case of going through the system to eliminate things as u progress

1 ) set the suspension into off road height , measure each wheels height , pull fuse F26 and leave for 24 hours to ensure there is no drop, i understand u say it doesn’t drop overnight but it’s to rule any air leak , as it will self level every 6 x hours when alarmed , by pulling the fuse u can see if any corner has dropped overnight

2) ensure inlet filter is clear in the boot, it’s a large black cyl type canister , has two filters inside , remove them and see with the compressor running if the same fault comes up,can u feel the air being sucked through the 6mm tube at the bottom of the air inlet with the compressor running , if the filters look dusty it’s better to replace them

3 ) was the correct relay fitted when the new amk compressor was fitted

4) see what the alternator volts are with the engine running , can go up 15.5 VDC volts, should be around a min of 14.4 VDC , it’s to ensure the correct volts are getting to the compressor and rules it out

5) plug a diagnostics reader in to see what the compressors output is producing , then also check the valve blocks operation, also see what the compressors temperature is

if it’s ok the easiest thing is to plug it into a diagnostic reader , that way u will get the pressure reading of the compressor and also u can at the same time test that the reservoir valve or corner valve are operating correctly

best to start there then onto a diagnostic reader , as it’s better than trying to change parts for the sake of it

also included a chart , it’s the pressures u should be looking for

hope that helps

johnlad said:

If the old compressor was failing there's a chance the pipe from compressor to the air reservoir is blocked with silica or even reservoir itself can have a pin prick on them, generally on top of them, if it's the original reservoir it's probably worth replacing anyway

Click to expand...

that happened to mine ref the silica and was a nightmare , in the end i had to replace

compressor
reservoir valve and air tank
front valve

still got to fit a new air silencer as the old one is broken on its clips and the pipes don’t look very good either, bought it months ago as a complete unit , just haven’t got round to fitting it, looks a pig to fit as it looks as though a wiring loom is also attached to the pipes

know the other favourite is the chaffing of wires behind the front passenger side wheel arch , causing intermittent errors

lynall said:

Garys your man and I bet he will answer this pdq

Click to expand...

have had plenty of experience with the EAS system, lol

Thanks guys for all your help and suggestions
johnlad hit the nail on the head, dropped the reservoir today an put it in a tub of water with 2 bar compressed air going into it.
Leaking from several holes along the seam. As I took the reservoir down I could feel a little bit of water sloshing around in it, so I immediately thought we might be onto something.
New tank arriving tomorrow.
Will post and advice if that finally fixes it.
Had already tried pulling the fuse and leaving it overnight, Through that I had found a slight leak on one of the rear air bag connections, new O ring seal cured that.
Thanks again everyone.

Looking on the bright side at least its not an expensive fix.

Hi Folks
Just to let you know this is now fixed. It was the air reservoir leaking. It looked fine from underneath, but when I removed it you could see a bit of rust bubbling through the paint along the seam - but no obvious holes.
so made up a connector and immersed in a tank of water with 2 bar air pressure inside, straight away I could see 2 or 3 streams of bubbles from the corroded areas.
New tank fitted. Long road test and it behaved. Its now been back in normal service for over week - including dragging a horsebox trailer and all is well.

Thanks for your help.