SOURCE: citroen c5 esp/asr system fault Whenever this warning light or any other stays on in the dash it is indicating that the systems control module (or the system sensor in the case of lights like low oil pressure, door open indicators etc.) has detected a fault, it then disables the system (this applies to ABS,TCS, TCM, SRS, TPMS, MIL, CEL and BCM faults and others) as long as the light is on. .

citroen c4 picasso obd location 2015