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Fault Code Map

One row per rule, from faults/registry.json. Legacy ID is the rule’s pre-renumbering code.

IDNameFamilyMethodStatusLegacy ID
AHU-0001Duct static pressure too low at full fan speedAHUruleverifiedAHU-FC-001
AHU-0002Mixed air temperature too lowAHUruleverifiedAHU-FC-002
AHU-0003Mixed air temperature too highAHUruleverifiedAHU-FC-003
AHU-0004Excessive operating state changes per hourAHUruleverifiedAHU-FC-004
AHU-0005SAT too low vs MAT in heatingAHUruleverifiedAHU-FC-005
AHU-0006OA fraction deviationAHUruleverifiedAHU-FC-006
AHU-0007SAT too low at full heatingAHUruleverifiedAHU-FC-007
AHU-0008SAT ≠ MAT in economizer modeAHUruleverifiedAHU-FC-008
AHU-0009OAT too high for free coolingAHUruleverifiedAHU-FC-009
AHU-0010OAT ≠ MAT in mechanical + economizer coolingAHUruleverifiedAHU-FC-010
AHU-0011OAT too low for mechanical coolingAHUruleverifiedAHU-FC-011
AHU-0012SAT too high vs MAT in coolingAHUruleverifiedAHU-FC-012
AHU-0013SAT too high at full coolingAHUruleverifiedAHU-FC-013
AHU-0014Inactive cooling coil temperature dropAHUruleverifiedAHU-FC-014
AHU-0015Inactive heating coil temperature riseAHUruleverifiedAHU-FC-015
AHU-0016Simultaneous heating and coolingAHUruleverifiedAHU-FC-050
AHU-0017Economizer not operational when favorableAHUruleverifiedAHU-FC-051
AHU-0018Unoccupied override — equipment running during off-hoursAHUruleverifiedAHU-FC-052
AHU-0019Supply air temperature setpoint too low (over-cooling)AHUruleverifiedAHU-FC-053
AHU-0020Stuck or failed actuatorAHUruleverifiedAHU-FC-054
AHU-0021Excess outdoor air during occupied hoursAHUruleverifiedAHU-FC-055
AHU-0022Supply air temperature hunting / oscillationAHUstatisticalverifiedAHU-FC-056
AHU-0023Supply air temperature reset not functioningAHUstatisticalverifiedAHU-FC-057
AHU-0024Duct static pressure reset not functioningAHUstatisticalverifiedAHU-FC-058
AHU-0025Heating or cooling coil lockout not active by OATAHUruleverifiedAHU-FC-059
AHU-0026Outdoor air damper not closed during unoccupied periodsAHUruleverifiedAHU-FC-060
AHU-0027Manual override detected on critical control pointAHUruleverifiedAHU-FC-061
AHU-0028Mixing box damper fault — MAT outside the OAT/RAT envelopeAHUruleverifiedAHU-FC-062
AHU-0029AHU operating mode mismatchAHUruleverifiedAHU-FC-063
AHU-0030Excess outdoor air during heating modeAHUruleverifiedAHU-FC-064
AHU-0031Supply fan operating at excessive static pressureAHUruleverifiedAHU-FC-065
AHU-0032SAT too high vs RAT in coolingAHUruleverifiedAHU-FC-066
AHU-0033Supply air temperature tracking errorAHUruleverifiedAHU-FC-067
AHU-0034Economizing past changeoverAHUruleverifiedAHU-FC-068
AHU-0035Supply air temperature too high for the zone populationAHUruleverified—
AHU-0036Duct static pressure too low for the zone populationAHUruleverified—
AHU-0037Economizing when it should not (damper position)AHUruleverified—
AHU-0038Cooling coil valve-position creep (fouling / authority loss)AHUstatisticalverified—
AHU-0039Supply fan proof-of-operation failureAHUruleverified—
CHW-0001Chiller efficiency (kW/ton) degradationCHWstatisticalverifiedCHW-FC-050
CHW-0002CHWST reset not functioningCHWstatisticalverifiedCHW-FC-051
CHW-0003CHW loop DP reset not functioningCHWstatisticalverifiedCHW-FC-052
CHW-0004Chilled water low delta-T syndromeCHWruleverifiedCHW-FC-053
CHW-0005Chiller condenser approach highCHWruleverifiedCHW-FC-054
CHW-0006Chiller evaporator approach highCHWruleverified—
CHW-0007Chilled-water supply temperature tracking failureCHWruleverified—
CHW-0008Chiller proof-of-operation failureCHWruleverified—
CHW-0009Chiller short-cyclingCHWruleverified—
ERV-0001Sensible effectiveness degradationERVstatisticalverifiedERV-FC-050
ERV-0002Frost protection not engagingERVruleverifiedERV-FC-051
ERV-0003Frost protection active above release conditionsERVruleverified—
ERV-0004Recovery device proof-of-operation failureERVruleverified—
ERV-0005Supply/exhaust airflow imbalanceERVruleverified—
FCU-0001Excessive operating state changesFCUruleverifiedFCU-FC-001
FCU-0002SAT too low in full heatingFCUruleverifiedFCU-FC-002
FCU-0003SAT too high in full coolingFCUruleverifiedFCU-FC-003
FCU-0004Inactive cooling coil temperature drop (leak)FCUruleverifiedFCU-FC-004
FCU-0005Inactive heating coil temperature rise (leak)FCUruleverifiedFCU-FC-005
FCU-0006FCU fan proof-of-operation failureFCUruleverified—
FCU-0007Simultaneous heating and cooling commandsFCUruleverified—
FPB-0001Terminal fan proof-of-operation failureFPBruleverified—
FPB-0002Primary airflow tracking failureFPBruleverified—
FPB-0003Reheat valve closed with unintended temperature riseFPBruleverified—
FPB-0004Terminal fan airflow degradationFPBstatisticalverified—
FPB-0005Primary airflow sensor disagreementFPBmetaverified—
FPB-0006Reheat-coil heat-transfer degradationFPBstatisticalverified—
HP-0001COP degradation vs baselineHPstatisticalverifiedHP-FC-050
HP-0002Defrost cycle anomalyHPruleverifiedHP-FC-051
HP-0003Reversing valve faultHPruleverifiedHP-FC-052
HP-0004Refrigerant undercharge — superheat/subcooling divergenceHPruleverifiedHP-FC-053
HP-0005Refrigerant overcharge — high liquid subcoolingHPruleverifiedHP-FC-054
HP-0006Reversing-valve internal bypass leakageHPruleverifiedHP-FC-055
HP-0007Heat-pump compressor proof-of-operation failureHPruleverified—
HP-0008Auxiliary heat active above lockout with compressor runningHPruleverified—
HW-0001Boiler short-cyclingHWruleverifiedHW-FC-050
HW-0002Boiler efficiency degradationHWstatisticalverifiedHW-FC-051
HW-0003Boiler or HW pump operating above OAT lockout temperatureHWruleverifiedHW-FC-052
HW-0004HW loop low delta-THWruleverifiedHW-FC-053
HW-0005HW loop DP too high (pump speed vs mild OAT)HWruleverifiedHW-FC-054
HW-0006HW loop DP reset not functioningHWstatisticalverifiedHW-FC-055
HW-0007HW supply temperature too high at low loadHWruleverifiedHW-FC-056
HW-0008HWS temperature reset not functioningHWstatisticalverifiedHW-FC-057
HW-0009Boiler proof-of-operation failureHWruleverified—
HW-0010Hot-water supply temperature tracking failureHWruleverified—
HW-0011Hot-water temperature-control huntingHWruleverified—
HW-0012Excess boiler stages at low plant loadHWruleverified—
HX-0001Hydronic heat-exchanger effectiveness degradationHXstatisticalverified—
HX-0002Heat exchanger active with one-side flow missingHXruleverified—
HX-0003Heat transfer persists with control valve commanded closedHXruleverified—
PMP-0001Pump commanded on, no flow detectedPMPruleverifiedPMP-FC-050
PMP-0002Pump deadheading (high DP, low/no flow)PMPruleverifiedPMP-FC-051
PMP-0003Pump proof-of-operation failurePMPruleverified—
PMP-0004Pump short-cyclingPMPruleverified—
PMP-0005Flow through stopped pumpPMPruleverified—
PMP-0006Pump input-power degradationPMPstatisticalverified—
RTU-0001Compressor short-cyclingRTUruleverifiedRTU-FC-050
RTU-0002Evaporator coil fouling — reduced temperature splitRTUstatisticalverifiedRTU-FC-051
RTU-0003Discharge and mixed air temperature inconsistency (AFDD0)RTUruleverifiedRTU-FC-052
RTU-0004Economizer not modulating properlyRTUruleverifiedRTU-FC-053
RTU-0005Excess outdoor air intakeRTUruleverifiedRTU-FC-054
RTU-0006Insufficient ventilation airRTUruleverifiedRTU-FC-055
RTU-0007Condenser airflow restriction (fouling)RTUstatisticalverifiedRTU-FC-100
RTU-0008Refrigerant undercharge — superheat/subcooling divergenceRTUruleverified—
RTU-0009Refrigerant overcharge — high liquid subcoolingRTUruleverified—
RTU-0010RTU supply-fan proof-of-operation failureRTUruleverified—
RTU-0011RTU supply-air temperature tracking failureRTUruleverified—
SYS-0001CHW flow with no cooling demandSYSruleverifiedSYS-FC-050
SYS-0002HW flow with no heating demandSYSruleverifiedSYS-FC-051
SYS-0003Lighting on with no occupancySYSruleverifiedSYS-FC-052
SYS-0004Exhaust fan running during unoccupied hoursSYSruleverifiedSYS-FC-053
SYS-0005Sensor drift via cross-validation (paired sensors)SYSruleverifiedSYS-FC-054
SYS-0006Virtual sensor drift detectionSYSstatisticalverifiedSYS-FC-055
SYS-0007Zone heating active during summer / warm weatherSYSruleverifiedSYS-FC-056
SYS-0008Exhaust fan schedule misalignment with AHUSYSruleverifiedSYS-FC-057
SYS-0009Sensor flatline while equipment activeSYSruleverifiedSYS-FC-058
SYS-0010Sensor spike / rate-of-change violationSYSruleverifiedSYS-FC-059
TOWER-0001Tower approach high at fan capacityTOWERruleverifiedTOWER-FC-050
TOWER-0002Tower range collapseTOWERruleverifiedTOWER-FC-051
TOWER-0003Tower fan short-cyclingTOWERruleverifiedTOWER-FC-052
TOWER-0004Tower fan proof-of-operation failureTOWERruleverified—
TOWER-0005Condenser water overcooling with fan energyTOWERruleverified—
TOWER-0006Cooling-tower basin freeze-protection failureTOWERruleverified—
VAV-0001VAV minimum airflow setpoint too highVAVruleverifiedVAV-FC-050
VAV-0002Rogue zone driving AHU resetVAVruleverifiedVAV-FC-051
VAV-0003Reheat valve open with zone satisfiedVAVruleverifiedVAV-FC-052
VAV-0004VAV airflow tracking errorVAVruleverifiedVAV-FC-053
VAV-0005VAV damper hunting or oscillationVAVruleverifiedVAV-FC-054
VAV-0006Reheat waste during cooling seasonVAVruleverifiedVAV-FC-055
VAV-0007VAV airflow tracking CUSUMVAVstatisticalverifiedVAV-FC-101
VAV-0008Zone temperature CUSUMVAVstatisticalverifiedVAV-FC-102
VAV-0009Reheat coil leakage CUSUMVAVstatisticalverifiedVAV-FC-103
VAV-0010Zone temperature sensor drift (neighbor-median)VAVstatisticalverified—
VFD-0001Command vs feedback deviationVFDruleverifiedVFD-FC-050
VFD-0002At minimum speed with load unsatisfiedVFDruleverifiedVFD-FC-051
VFD-0003At maximum speed with load unsatisfiedVFDruleverified—
VFD-0004VFD process-loop huntingVFDruleverified—
VFD-0005VFD not in remote automatic controlVFDruleverified—