DTC C1A20-64: Pressure Increase Too Slow When Filling Reservoir - Signal plausibility failure: Action

NOTE: The rate of pressure increases when the reservoir is being charged, should remain within known limits. The DTC is set if the rate of increase of pressure is too low

Check the expansion air chamber for an air leak. If a leak is identified, install a new expansion chamber as required. For additional information, Refer to: VEHICLE DYNAMIC SUSPENSION
Check the gallery pipes and reservoir pipes for leaks, correct routing and installation. Check the integrity of the air reservoir. Repair/renew as required, clear the DTCs and retest
Check gallery pipe to front valve block fitted correctly and free from leaks
Refer to the approved diagnostic system for corner, reservoir and exhaust valve checks. Check the corner valve for leaks. Repair/renew as required, clear the DTCs and retest
Check the air suspension air supply unit intake filter, intake pipe and silencer for blockages/restrictions. Repair as required, clear the DTCs and retest
Check the operation of the air suspension air supply unit. Repair or replace as required, clear the DTCs and retest