Mercedes-Benz W212 air suspension height sensor and level calibration
The W212 S212 rear is at the wrong height, what is checked on the height sensor?
Check the sensor rods and their ball joints. They can rust or get dirty and seize, and a seized rod can bend the sensor's mounting plate so that the sensor shows the wrong height. Cleaning and lubrication help, but a worn joint can stay loose and seize again. The sensor wiring should be checked before replacing the sensor.
Does the air suspension height have to be calibrated after repairing the bags or lines?
Yes. The level control calibration is done in the diagnostic tool's calibration mode, after which automatic calibration starts. From the sensor values shown in calibration mode you can tell whether the bracket of the level link is bent. The measurement from the arch to the wheel hub on the S212 is 365 mm, and it can vary on uneven ground.
Why does the W212 S212 rear rise too high after replacing air suspension parts?
One reason is the wrong order of the valve block lines: the right-side line is marked red and the left blue. Also an air dryer clogged in freezing weather or a broken pressure relief valve wire can keep the rear up. The wire can put the level control into limp mode, so the car does not try to adjust the height. Air suspension is pressurised and affects driving safety, so leave opening the lines and replacing air springs to a workshop.