DOC AIRBUS | AMM A320FOIL FILTER CLOGGING WARNING SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. Oil Differential Pressure Switch
** ON A/C NOT FOR ALL 
Oil Differential Pressure-Switch - Location- The oil differential pressure switch is bracketed on the engine above the scavenge filter. Lines are routed to the switch from bosses on the scavenge filter.
- Actuation of the differential pressure switch is at:
25.5 plus or minus 1 PSID increasing pressure
22 PSID decreasing pressure.
2. Oil Filter Clogging Indication
When the differential pressure through the oil scavenge filter is:
In result:
When the differential pressure through the oil scavenge filter is:
- higher than 25.5 plus or minus 1 PSID increasing pressure, the switch closes.
- ENG page on the lower display unit of the ECAM appears:
OIL FILTER CLOG indication (White and Amber) - instructions appears on the upper display unit of the ECAM.
In result:
- the clogging indication on the ENG ECAM page disappears,
- the MASTER CAUT light goes off,
- the audio warning is de-activated,
- the instructions on the upper display unit disappear.