Pneumatic Supply Pressure
Erase fault memory and check if fault is still present. If fault is still present exchange faulty pressure sensor to fix the problem.
What you'll see
No driver-visible symptom recorded.
System reaction
System pressure can only be calculated out of one sensor in case that one sensor value from circuit 21 or circuit 22 was identified as stucked. The stucked sensor value will be set to invalid on AIR1 message.
Diagnostic depth
Immediately after switching the compressor solenoid valve, either 'on' or 'off', reference values of the pressures in circuit 21 and circuit 22 are stored. If the difference between reference value and current value of one circuit is above (+/-) 500 mbar for 2 seconds and the pressure difference of the other circuit is less than (+/-) 200 mbar the failure is detected when these both conditions are fulfilled and the pressure value of the circuit with the at least 500 mbar difference is above the minimum working pressure of the charging valve.
Difference between pressure 21 and pressure 22 is above the limit. A stucked sensor was detected.