Thermo King Alarm 509: ECU Failed to Enable
Alarm 509 is listed as 'ECU Failed to Enable' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Error Codes
Browse published fault-code records by brand, product and displayed code.
Each record starts with the source meaning, then separates applicability, owner-safe actions, operating uncertainty and qualified-service boundaries. A matching code string alone is not enough: confirm the brand, product, model and controller before acting.
Thermo King Alarm 510: ECU Run Signal Failed
Alarm 510 is listed as 'ECU Run Signal Failed' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 511: Engine Wait to Start Time Delay Expired
Alarm 511 is listed as 'Engine Wait to Start Time Delay Expired' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 512: High Compressor Suction Pressure (Scroll Only)
Alarm 512 is listed as 'High Compressor Suction Pressure (Scroll Only)' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 513: Low Compressor Suction Ratio (Scroll Only)
Alarm 513 is listed as 'Low Compressor Suction Ratio (Scroll Only)' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 514: Low Compressor Discharge Pressure (Scroll Only)
Alarm 514 is listed as 'Low Compressor Discharge Pressure (Scroll Only)' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 515: Minimum ETV Discharge Superheat Temp (Scroll)
Alarm 515 is listed as 'Minimum ETV Discharge Superheat Temp (Scroll)' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 516: I/O Controller to Application Controller Com Failure
Alarm 516 is listed as 'I/O Controller to Application Controller Com Failure' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 518: Generator Ground Fault
Alarm 518 is listed as 'Generator Ground Fault' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 519: Check Battery Charger Input Power
Alarm 519 is listed as 'Check Battery Charger Input Power' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 520: Check Battery Charger Output Power
Alarm 520 is listed as 'Check Battery Charger Output Power' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 521: Battery Charger External/Environmental Fault
Alarm 521 is listed as 'Battery Charger External/Environmental Fault' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 522: Battery Temperature Sensor Alarm
Alarm 522 is listed as 'Battery Temperature Sensor Alarm' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 523: Battery Charger Indicated Conditions
Alarm 523 is listed as 'Battery Charger Indicated Conditions' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 524: Generator Op Limit Vout to Frequency Ration
Alarm 524 is listed as 'Generator Op Limit Vout to Frequency Ration' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 525: Generator Frequency Range Fault
Alarm 525 is listed as 'Generator Frequency Range Fault' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 526: Generator Operational Limit Output Current
Alarm 526 is listed as 'Generator Operational Limit Output Current' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 528: Failed J1939 CAN Comm Base Controller/Charger
Alarm 528 is listed as 'Failed J1939 CAN Comm Base Controller/Charger' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 529: Check Fuel Pump Circuit
Alarm 529 is listed as 'Check Fuel Pump Circuit' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 530: Low Pressure Differential (Scroll only)
Alarm 530 is listed as 'Low Pressure Differential (Scroll only)' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 531: Check Economizer Pressure Sensor (Scroll only)
Alarm 531 is listed as 'Check Economizer Pressure Sensor (Scroll only)' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 538: Engine J1939 CAN Data Link Degraded
Alarm 538 is listed as 'Engine J1939 CAN Data Link Degraded' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 539: Engine J1939 CAN Data Link Failed
Alarm 539 is listed as 'Engine J1939 CAN Data Link Failed' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 540: Illegal Engine Operating State
Alarm 540 is listed as 'Illegal Engine Operating State' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01