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boiler service, boiler repair, emergency repair
Vaillant ecoTEC pro 28 LPG Boiler Fault Codes
| Code | Meaning | Cause |
| F00 | Flow temperature sensor interruption | NTC plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, NTC defective |
| F01 | Return temperature sensor interruption | NTC plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, NTC defective |
| F10 | Flow NTC short circuit | NTC defective, short circuit in cable harness, cable/casing |
| F11 | Return NTC short circuit | NTC defective, short circuit in cable harness, cable/casing |
| F20 | Safety switch-off: temperature limiter | Incorrect earth connection between cable harness and boiler, flow or return NTC defective (loose connection), black discharge via ignition cable, ignition plug or ignition electrode |
| F22 | Safety switch-off: low water pressure | No or to low water pressure in the boiler, water pressure sensor defective, cable to pump or water pressure sensor loose/not connected/defective |
| F23 | Safety switch-off: Temperature difference too great | Pump blocked, insufficient pump output, air in boiler, flow and return NTC interchanged |
| F24 | Safety switch-off: Temperature rise too fast | Pump blocked, poor pump performance, air in boiler, system pressure too low, non-return valve blocks/incorrectly installed |
| F25 | Safety switch-off: Flue gas temperature too high | Break in plug connection for optional flue gas safety thermostat (STB), break in cable harness |
| F26 | Fault: Gas valve without function | Gas valve stepper motor not connected, multiple plug on the PCB not plugged in correctly, interruption in cable harness, gas valve stepper motor defective, electronics defective |
| F27 | Safety switch-off: Flame simulation | Moisture on the electronics, electronics (flame monitor) defective, gas solenoid valve leaking |
| F28 | Failure during start-up: ignition unsuccessful | Gas meter defective or gas pressure regulator has triggered, air in gas, gas flow pressure too low, thermal isolator device (TAE) has triggered, condensate duct blocked, incorrect gas restrictor, incorrect ET gas valve, fault on the gas valve, multiple plug on PCB incorrectly plugged in, break in cable harness, ignition system (ignition transformer, ignition cable, ignition plug, ignition electrode) defective, ionisation current interrupted (cable, electrode), incorrect earthing of boiler, electronics defective |
| F29 | Failure during operation: Re-ignition unsuccessful | Gas supply temporarily stopped, flue gas recirculation, condensate duct blocked, faulty earthing of boiler, ignition transformer has spark failure |
| F32 | Fan fault | Plug at fan not correctly plugged in, multiple plug on PCB not correctly plugged in, break in cable harness, fan blocked, Hall sensor defective, electronics defective |
| F49 | eBUS fault | Short circuit on eBUS, eBUS overload or two power supplies with different polarities on the eBUS |
| F61 | Gas valve actuation fault |
The gas valve cannot be actuated – Cable harness supply line to the gas valve is defective (short to earth, short circuit) – Gas valve defective – PCB defective |
| F62 | Fault: Gas valve switch-off delay |
Delayed shutdown of gas valve detected – Secondary light (ignition and monitoring electrode indicates delayed extinguishing of the flame signal) – Gas valve defective – PCB defective |
| F63 | EEPROM error | Electronics defective |
| F64 | Electronics/NTC fault | Flow or return NTC short circuited, electronics defective |
| F65 | Electronic temperature fault | Electronics overheating due to external influences, electronics defective |
| F67 | Electronics/flame fault | Implausible flame signal, electronics defective |
| F68 | Unstable flame signal fault | Air in gas, gas flow pressure too low, wrong air ratio, condensate route blocked, wrong gas restrictor, ionisation flow interruption (cables, electrodes), flue gas recirculation, condensate route |
| F70 | Invalid device specific number (DSN) | Spare part case: Display and PCB replaced at same time and DSN not set, wrong or missing output range coding resistor |
| F71 | Flow NTC fault |
Flow temperature sensor signalling constant value: - Flow temperature sensor incorrectly positioned at supply pipe. - Flow temperature sensor defective. |
| F72 | Flow/return NTC fault | Flow/return NTC temperature difference too great -> flow and/or return temperature sensor defective |
| F73 | Water pressure sensor signal in the wrong range (too low) | Interruption/short circuit of water pressure sensor, interruption/short circuit to GND in supply line to water pressure sensor or water pressure sensor defective |
| F74 | Water pressure sensor signal outside correct range (too high) | Cable to water pressure sensor has short-circuited at 5 V/24 V or internal fault in water pressure sensor |
| F75 | Fault, no pressure change detection when starting pump | Water pressure sensor and/or pump defective, air in heating installation, too low water pressure in boiler; check adjustable bypass, connect external expansion vessel to return |
| F77 | Flue non-return flap/condensate pump fault | No response from flue non-return flap or condensate pump defective |
| F78 | Interruption to DHW outlet sensor at external controller | UK link box is connected, but hot water NTC not bridged |
| F83 | Flow and/or return temperature sensor temperature change fault |
When the burner starts, the temperature change registered at flow and/or return temperature sensor is non-existent or too small. - Not enough water in the boiler - Flow and/return temperature sensor not in correct position at pipe. |
| F84 | Fault: Flow/return temperature sensor temperature difference implausible |
Flow and return temperature sensors returning implausible values. - Flow and return temperature sensors have been inverted. - Flow and return temperature sensors have not been correctly fitted. |
| F85 | Fault: Flow and return temperature sensors incorrectly fitted | Flow and/or return temperature sensors have been fitted to the same pipe/wrong pipe. |
| Communication fault | No communication with the PCB | Communication fault between display and PCB in the electronics box |