Thermo 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 2026-05-01Error 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 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 2026-05-01Thermo King Alarm 542: Battery Charger Fault – Unit Forced to Low Speed
Alarm 542 is listed as 'Battery Charger Fault – Unit Forced to Low Speed' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 543: Battery Charger Internal Short
Alarm 543 is listed as 'Battery Charger Internal Short' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 544: Battery Charger External Short
Alarm 544 is listed as 'Battery Charger External Short' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 545: Battery Charger Output Voltage Exceeded Limit
Alarm 545 is listed as 'Battery Charger Output Voltage Exceeded Limit' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 546: Battery Charger Operating Bulk Voltage Out of Range
Alarm 546 is listed as 'Battery Charger Operating Bulk Voltage Out of Range' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 547: AC Bus Phase Loss
Alarm 547 is listed as 'AC Bus Phase Loss' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 548: Battery Charger Temperature Below Operating Range
Alarm 548 is listed as 'Battery Charger Temperature Below Operating Range' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 549: Battery Charger AC Input Overvoltage
Alarm 549 is listed as 'Battery Charger AC Input Overvoltage' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 550: Battery Charger Internal Overvoltage Fault
Alarm 550 is listed as 'Battery Charger Internal Overvoltage Fault' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 599: Engine Service Tool Connected
Alarm 599 is listed as 'Engine Service Tool Connected' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 600: Check Crankshaft Speed Sensor
Alarm 600 is listed as 'Check Crankshaft Speed Sensor' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 601: Check Camshaft Speed Sensor
Alarm 601 is listed as 'Check Camshaft Speed Sensor' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 603: Check Exhaust Pressure Sensor
Alarm 603 is listed as 'Check Exhaust Pressure Sensor' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 604: Check Coolant Temp Sensor
Alarm 604 is listed as 'Check Coolant Temp Sensor' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01Thermo King Alarm 605: Check Fresh Air Temp Sensor
Alarm 605 is listed as 'Check Fresh Air Temp Sensor' for Thermo King Truck/Trailer Refrigeration Unit. Verify the exact model and controller before acting.
Source checked 2026-05-01