Look up an alarm or trip code from a plant utility controller. Each entry explains what the code usually means, the most likely causes, and the checks an operator can make safely before calling a specialist. The current entries are generic examples grouped by utility — use them to structure your investigation, then confirm the exact meaning in your equipment manual. You can also browse the troubleshooting guides .
C-215 Critical Chiller
Generic Chiller Co · Chiller (generic model)
Probable causes Leaving chilled water setpoint too low Low flow Sensor drift Step-by-step checks Stop and do not bypass protection Check setpoint and flow Verify sensor calibration Safety: Refrigerant work requires certified technicians; isolate power before panel access.
Sample code — verify with the OEM manual for your exact model.
E-201 Trip Chiller
Generic Chiller Co · Chiller (generic model)
Probable causes Fouled condenser tubes Low condenser water flow High cooling-water temperature Non-condensables in refrigerant Step-by-step checks Check condenser approach temperature Verify condenser water flow and pump status Check cooling tower performance Arrange qualified refrigerant check Safety: Refrigerant work requires certified technicians; isolate power before panel access.
Sample code — verify with the OEM manual for your exact model.
E-202 Trip Chiller
Generic Chiller Co · Chiller (generic model)
Probable causes Low refrigerant charge Low chilled-water flow Expansion valve fault Step-by-step checks Check chilled-water flow and strainer Record suction pressure and superheat Arrange qualified leak check Safety: Refrigerant work requires certified technicians; isolate power before panel access.
Sample code — verify with the OEM manual for your exact model.
E-203 Trip Chiller
Generic Chiller Co · Chiller (generic model)
Probable causes Pump trip Closed valve Clogged strainer Faulty flow switch Step-by-step checks Confirm pump running Walk the chilled-water valve line-up Check strainer dP Test flow switch Safety: Refrigerant work requires certified technicians; isolate power before panel access.
Sample code — verify with the OEM manual for your exact model.
W-210 Warning Chiller
Generic Chiller Co · Chiller (generic model)
Probable causes High head pressure Low voltage Mechanical wear Step-by-step checks Record amps and voltage Check condenser conditions Compare with OEM full-load amps Safety: Refrigerant work requires certified technicians; isolate power before panel access.
Sample code — verify with the OEM manual for your exact model.
W-220 Warning Chiller
Generic Chiller Co · Chiller (generic model)
Probable causes Low oil level Oil filter blocked Refrigerant dilution Step-by-step checks Check oil level and heater Inspect oil filter dP Contact OEM service if persistent Safety: Refrigerant work requires certified technicians; isolate power before panel access.
Sample code — verify with the OEM manual for your exact model.
C-406 Critical Cooling Tower
Generic Cooling Towers · Cooling Tower (generic model)
Probable causes Biocide dosing failure Stagnant water Step-by-step checks Follow site water hygiene procedure Check dosing pump Contact water treatment specialist Safety: Lock out fans before entry; use respiratory protection near drift.
Sample code — verify with the OEM manual for your exact model.
E-401 Trip Cooling Tower
Generic Cooling Towers · Cooling Tower (generic model)
Probable causes Blade imbalance or damage Loose mounting Gearbox wear Step-by-step checks Isolate and lock out fan Inspect blades and pitch Check gearbox oil and mounting bolts Safety: Lock out fans before entry; use respiratory protection near drift.
Sample code — verify with the OEM manual for your exact model.
E-404 Trip Cooling Tower
Generic Cooling Towers · Cooling Tower (generic model)
Probable causes Blade pitch too high Low voltage Bearing failure Step-by-step checks Check blade pitch against design Measure motor current Inspect bearings after isolation Safety: Lock out fans before entry; use respiratory protection near drift.
Sample code — verify with the OEM manual for your exact model.
W-402 Warning Cooling Tower
Generic Cooling Towers · Cooling Tower (generic model)
Probable causes Clogged fill Poor water distribution High wet-bulb temperature Fan running slow Step-by-step checks Calculate approach to wet-bulb Inspect nozzles and fill Verify fan speed Safety: Lock out fans before entry; use respiratory protection near drift.
Sample code — verify with the OEM manual for your exact model.
W-403 Warning Cooling Tower
Generic Cooling Towers · Cooling Tower (generic model)
Probable causes Make-up valve fault Excess blowdown Leak Step-by-step checks Check make-up valve and float Inspect basin for leaks Review blowdown rate Safety: Lock out fans before entry; use respiratory protection near drift.
Sample code — verify with the OEM manual for your exact model.
W-405 Warning Cooling Tower
Generic Cooling Towers · Cooling Tower (generic model)
Probable causes Low blowdown Make-up quality change Step-by-step checks Check conductivity controller Test make-up water Adjust blowdown with water treatment supplier Safety: Lock out fans before entry; use respiratory protection near drift.
Sample code — verify with the OEM manual for your exact model.
C-505 Critical Nitrogen Generator
Generic Nitrogen Gen · Nitrogen Generator (generic model)
Probable causes Nitrogen leak in enclosed room Poor ventilation Step-by-step checks Evacuate and do not enter Ventilate per site procedure Only trained personnel with gas monitors may investigate Safety: Nitrogen is an asphyxiant; check oxygen levels before entering enclosed spaces.
Sample code — verify with the OEM manual for your exact model.
E-501 Trip Nitrogen Generator
Generic Nitrogen Gen · Nitrogen Generator (generic model)
Probable causes Feed air too wet or oily Carbon molecular sieve degraded Flow above rating Step-by-step checks Check feed air dew point and filters Reduce flow to rated value Arrange purity analyser check Safety: Nitrogen is an asphyxiant; check oxygen levels before entering enclosed spaces.
Sample code — verify with the OEM manual for your exact model.
E-503 Trip Nitrogen Generator
Generic Nitrogen Gen · Nitrogen Generator (generic model)
Probable causes Pilot air loss Solenoid failure Valve seat wear Step-by-step checks Check pilot air supply Test solenoid coils Inspect valve per OEM procedure Safety: Nitrogen is an asphyxiant; check oxygen levels before entering enclosed spaces.
Sample code — verify with the OEM manual for your exact model.
W-502 Warning Nitrogen Generator
Generic Nitrogen Gen · Nitrogen Generator (generic model)
Probable causes Compressor capacity Blocked filters Leaks Step-by-step checks Check inlet pressure gauge Inspect pre-filters Leak-test feed line Safety: Nitrogen is an asphyxiant; check oxygen levels before entering enclosed spaces.
Sample code — verify with the OEM manual for your exact model.
W-504 Warning Nitrogen Generator
Generic Nitrogen Gen · Nitrogen Generator (generic model)
Probable causes Sensor end of life Calibration due Step-by-step checks Check analyser status Calibrate with reference gas Replace sensor per OEM interval Safety: Nitrogen is an asphyxiant; check oxygen levels before entering enclosed spaces.
Sample code — verify with the OEM manual for your exact model.
W-506 Warning Nitrogen Generator
Generic Nitrogen Gen · Nitrogen Generator (generic model)
Probable causes Dryer fault upstream Drain trap failure Step-by-step checks Check dryer operation Test drain traps Record dew point Safety: Nitrogen is an asphyxiant; check oxygen levels before entering enclosed spaces.
Sample code — verify with the OEM manual for your exact model.
C-305 Critical Screw Air Compressor
Generic Air Systems · Screw Air Compressor (generic model)
Probable causes Phase sequence reversed after electrical work Wiring error Step-by-step checks Do not restart repeatedly Have a qualified electrician verify phase sequence Bump-test only per OEM procedure Safety: Isolate electrically and vent all stored air pressure before opening any part.
Sample code — verify with the OEM manual for your exact model.
E-101 Trip Screw Air Compressor
Generic Air Systems · Screw Air Compressor (generic model)
Probable causes Low oil level Blocked oil cooler fins Faulty thermostatic valve High ambient/intake temperature Step-by-step checks Check oil level at sight glass with unit stopped Inspect and clean cooler fins Verify cooling air path and room ventilation Check thermostatic valve operation against OEM data Safety: Isolate electrically and vent all stored air pressure before opening any part.
Sample code — verify with the OEM manual for your exact model.
E-102 Trip Screw Air Compressor
Generic Air Systems · Screw Air Compressor (generic model)
Probable causes High system pressure setting Low supply voltage or phase imbalance Worn bearings Loose terminals Step-by-step checks Check set pressure against rated pressure Measure voltage and current on all phases (qualified electrician) Inspect terminal tightness after isolation Listen for bearing noise Safety: Isolate electrically and vent all stored air pressure before opening any part.
Sample code — verify with the OEM manual for your exact model.
E-110 Trip Screw Air Compressor
Generic Air Systems · Screw Air Compressor (generic model)
Probable causes Damaged sensor cable Failed transducer Moisture in connector Step-by-step checks Inspect sensor cable and connector Compare reading with a calibrated gauge Replace transducer if out of range Safety: Isolate electrically and vent all stored air pressure before opening any part.
Sample code — verify with the OEM manual for your exact model.
W-203 Warning Screw Air Compressor
Generic Air Systems · Screw Air Compressor (generic model)
Probable causes Dirty intake filter Dusty compressor room Wrong filter element Step-by-step checks Read filter dP on controller Inspect and replace intake filter Check room for dust sources Safety: Isolate electrically and vent all stored air pressure before opening any part.
Sample code — verify with the OEM manual for your exact model.
W-204 Warning Screw Air Compressor
Generic Air Systems · Screw Air Compressor (generic model)
Probable causes Saturated separator element Degraded oil Carry-over from high temperature Step-by-step checks Record separator dP trend Check oil condition and service hours Plan separator replacement per OEM interval Safety: Isolate electrically and vent all stored air pressure before opening any part.
Sample code — verify with the OEM manual for your exact model.
C-320 Critical Steam Boiler
Generic Boiler Works · Steam Boiler (generic model)
Probable causes Pressure control fault Stuck modulating control Sudden load drop Step-by-step checks Confirm safety valves are in service Check pressure controller and switch Do not adjust limit settings without authorisation Safety: Boiler work must follow site permit-to-work; never bypass safety controls.
Sample code — verify with the OEM manual for your exact model.
E-301 Trip Steam Boiler
Generic Boiler Works · Steam Boiler (generic model)
Probable causes Feed pump failure Level control fault Excess blowdown Steam demand surge Step-by-step checks Do not add water to a hot dry boiler — call a competent person Check gauge glass and feed pump Test level controls per site procedure Safety: Boiler work must follow site permit-to-work; never bypass safety controls.
Sample code — verify with the OEM manual for your exact model.
E-302 Trip Steam Boiler
Generic Boiler Works · Steam Boiler (generic model)
Probable causes Fouled flame sensor Fuel supply interruption Poor air/fuel ratio Ignition fault Step-by-step checks Check fuel pressure Inspect and clean flame sensor Verify purge and ignition sequence Safety: Boiler work must follow site permit-to-work; never bypass safety controls.
Sample code — verify with the OEM manual for your exact model.
E-340 Trip Steam Boiler
Generic Boiler Works · Steam Boiler (generic model)
Probable causes Fan motor overload Damper linkage fault Air proving switch fault Step-by-step checks Check fan motor and overload Inspect damper linkage Test air proving switch Safety: Boiler work must follow site permit-to-work; never bypass safety controls.
Sample code — verify with the OEM manual for your exact model.
W-310 Warning Steam Boiler
Generic Boiler Works · Steam Boiler (generic model)
Probable causes Sooted fire tubes Scale on water side High excess air Step-by-step checks Record stack temperature trend Plan tube cleaning Check flue-gas O2 Safety: Boiler work must follow site permit-to-work; never bypass safety controls.
Sample code — verify with the OEM manual for your exact model.
W-330 Warning Steam Boiler
Generic Boiler Works · Steam Boiler (generic model)
Probable causes Insufficient blowdown Feedwater quality problem Step-by-step checks Check TDS reading Verify blowdown valve operation Check water treatment Safety: Boiler work must follow site permit-to-work; never bypass safety controls.
Sample code — verify with the OEM manual for your exact model.
