Mercedes-Benz W220 Airmatic: corner won't rise or lower, height sensors and valve block
W220 Airmatic: why won't one corner rise or lower?
The cause can be the height sensor, a solenoid valve or the valve block (distribution valve). Sensors rust and seize, and valves oxidise or get dirty. The sensor bracket can also break. Start by reading the fault codes.
W220: fault code for a solenoid valve, what should I check?
Measure the voltage at the valve and check the wiring between the valve and the control unit, as well as oxidation of the connectors. The valve can be faulty even if it is given direct power. In that case the whole valve block is replaced.
W220: why won't the air suspension rise even though the compressor runs?
Air may not be passing through the valve block, or pressure is leaking away. Check the fuses and relay belonging to the air suspension and the compressor's air filters. It is worth measuring the pressure with a Mercedes-Benz diagnostic tool between the compressor and the valve block.
W220: why does the car rise or lower by itself while parked?
The valve block can leak or stick when cold, letting pressure run from the pressure reservoir into the air bags. A new or exchange block can also be faulty. The leak is located with a diagnostic tool. Air suspension is pressurised and affects driving safety, so leave opening the lines and replacing air springs to a workshop.