Mercedes-Benz W212 air suspension pressure relief valve fault code (C155E13, 555E)
The W212 Airmatic shows fault code C155E13 or 555E, what does it mean?
The codes point to the electrical circuit of the air suspension pressure relief valve. The fault does not always mean the valve itself is broken; there may be an open circuit or a poor connection in the circuit.
What usually causes an Airmatic pressure relief valve fault code?
The typical cause is the valve's wire, which has broken near the compressor connector. The plastic sheath can look intact even though the wire is broken or corroded inside. The wire can also have been chafed through by the sharp edge of a cable tie.
How can the pressure relief valve's operation be tested?
You can apply 12 volts, at most 750 mA, to the valve terminals and see whether the valve moves. If it moves, the fault is probably in the wire or the connector. Repair the wire and connector before replacing the valve. When the valve opens, pressure escapes from the system and the car can drop, so do not be under the car during the test.