Afternoon, ive got a 2003 l322 (diesel engine). Ive got an issue with the air suspension its dropped to the bump stops but their is no fault code and the dash light is in normal road mode.
I borrowed a snap on diagnostic reader to see what the live data was saying.
1st thing i noticed was the target for the air res was 9bar but the sensor was only reading 8.1bar, so got under the car and unplugged it and the reading went up to 20 something so can assume the wiring wasnt at fault (ive ordered a new sensor).
We then checked that the pump in the boot is operating which it is, its getting pretty hot though reading 52 degrees at one point. I allowed the pump to cool and flicked the switch into off road mode & the pump didnt fire up. I then put the switch back into road mode and the pump fired and ran for around 30 secs and cut out.
Whilst doing this i was watching the live data and at no point does the air res valve open.
So i guess my questions are when should the res valve open? Will changing the res sensor make any difference? And why dont i have any fault codes?
Cheers for your help in advance.


Oh unrelated to my car but save a new thread my father in laws 2006 sport's steering is off centre and ideas why? (Hes had the tracking done about a month ago)

No idea on the former but regarding the latter.....he either hit something or another named driver hit something within the last month.
He would not of accepted an 'off' steering wheel after alignment would he.

Suspension could be any number of things pump is possible but car should lock at road height, could be an air pipe leaking somewhere, or the air tank. It's normal for the pump to run and cut out if it senses it's not putting pressure into the system.

How olds the pump. It won't sense any increase if it's not pumping air out

No idea how old the pump is i can only assume that its orignal, its pumping air i took the pipe off in the boot and checked. ive ordered a new valve block aswell but that wont be here for another week. I couldnt find anything that was leaking, and its not locked in road mode, its sat on its arse but the lights on the dash say its on road mode and u can select off road or access on the dash, it just doesnt move

RRkev said:

Suspension could be any number of things pump is possible but car should lock at road height, could be an air pipe leaking somewhere, or the air tank. It's normal for the pump to run and cut out if it senses it's not putting pressure into the system.

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So in order to put air into the system surely the reservior valve needs to open in order for air to fill the tank?? Or does the valve only open to release air into the bags?

I'm not 100% sure on that, it's a complex system, if there is a problem with the air tank or the pump the car should lock in road height, or even if there is a fault it should also stay at road height. Any air exhausted from the system should be done at the pump, one way to test would be to use a small compressor (garage type with an air tank) and cobble a tyre pressure gauge on to the main air input pipe them slowly & carefully add air to the system. Worst case scenario you'll find a leak, best case car will rise.


I still think you have a leak somewhere personally, I don't think you'd be unlucky and have 4 airbags go together though.

RRkev said:

I'm not 100% sure on that, it's a complex system, if there is a problem with the air tank or the pump the car should lock in road height, or even if there is a fault it should also stay at road height. Any air exhausted from the system should be done at the pump, one way to test would be to use a small compressor (garage type with an air tank) and cobble a tyre pressure gauge on to the main air input pipe them slowly & carefully add air to the system. Worst case scenario you'll find a leak, best case car will rise.


I still think you have a leak somewhere personally, I don't think you'd be unlucky and have 4 airbags go together though.

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Yer i tried putting air into the system from the pipe off the pump, had all the doors and boot closed, as it wont operate with them open, still didnt seem to take air thought it maybe due to the res valve not opening as i could feel the pressure building in the line, so got a mate in the front to flick the switch while trying to pump air in still nothing.

it is most likely the main valve block located on the front of the tank under a plastic cover, maybe easier to locate the pipe from the compressor and crack it open to see if you have air coming through to the valve.

Ive ordered one of those aswell, been waiting almost 3 weeks for it to arrive.