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boiler service, boiler repair, emergency repair
Vaillant ecoTEC exclusive 835 Boiler Fault Codes
| Code | Parameter | Possible Causes |
| F00 | Interruption: Flow sensor | 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 | Interruption: Return sensor | NTC plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, NTC defective |
| F02 | Interruption: DHW outlet sensor | Only in conjunction with F91 NTC defective, NTC cable defective, defective plug connection on NTC, defective plug connection on the actoSTOR electronics |
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F03 |
Interruption: Cylinder sensor | Only in conjunction with F91 NTC defective, NTC cable defective, defective plug connection on NTC, defective plug connection on the actoSTOR electronics |
| F10 | Short circuit: Flow sensor | NTC defective, short circuit in cable harness, cable/housing |
| F11 | Short circuit: Return sensor | NTC defective, short circuit in cable harness, cable/housing |
| F12 | Short circuit: DHW outlet sensor | Only in conjunction with F91 NTC defective, short circuit in cable harness, cable/housing |
| F13 | Short circuit: Cylinder sensor | Combination product: Warm start sensor/cylinder sensor short circuit Combination product with actoSTOR: Short circuit cylinder sensor (NTC) only in combination with F91 NTC defective, short circuit in cable harness, cable/housing |
| F20 | Safety switch-off: Temperature limiter | Incorrect earth connection between cable harness and product, flow or return NTC defective (loose connection), stray spark via ignition cable, ignition plug or ignition electrode |
| F22 | Safety switch-off: Low water pressure | No or insufficient water in the product, water pressure sensor defective, cable to pump or water pressure sensor loose/not connected/defective |
| F23 | Safety switch-off: Temp.spread too large | Pump blocked, insufficient pump output, air in product, flow and return NTC connected the wrong way round |
| F24 | Safety switch-off: Temp. incr. too fast | Pump blocked, insufficient pump output, air in product, system pressure too low, non-return valve blocked/incorrectly installed |
| F25 | Safety switch-off: Flue temp. too high | Break in plug connection for optional flue gas safety cut-out (SCO), break in cable harness |
| F26 | Fault: Fuel valve not working | Gas valve assembly stepper motor not connected, multiple plug on the PCB not plugged in correctly, interruption in cable harness, gas valve assembly stepper motor defective, electronics defective |
| F27 | Safety switch-off: Flame simulation | Moisture on the electronics, electronics (flame monitor) defective, gas solenoid valve leaking |
| F28 | Start-up failure: Ignit. unsuccessful | Gas meter defective or gas flow monitor has triggered, air in gas, gas flow pressure too low, thermal isolator device (TAE) has triggered, condensate route blocked, incorrect gas injector, incorrect spare part gas valve assembly, value in D.052 does not correspond to the printed value on the current gas valve assembly, fault on the gas valve assembly, multiple plug on PCB incorrectly plugged in, break in cable harness, ignition system (ignition transformer, ignition cable, ignition plug, ignition electrode) defective, ionisation flow interrupted (cable, electrode), incorrect earthing of product, electronics defective |
| F29 | Start-up failure: Ignit. unsuccessful | Gas supply temporarily stopped, flue gas recirculation, condensate route blocked, defective earthing of product, ignition transformer has spark failure |
| F32 | Fault: Fan | Plug on fan not correctly plugged in, multiple plug on PCB not correctly plugged in, break in cable harness, fan blocked, Hall sensor defective, electronics defective |
| F33 | Pressure switch | Check: Cable harness, vacuum hose (blockage), supply air/flue gas route (blockage), panel (correct type), flue pipe (length), air pressure sensor, settings (if necessary, switch D132 to multiple-flue configuration), pressure switch, fan. |
| F35 | Fault: Air/flue gas duct |
Check the entire air/flue pipe for: – Permitted design – Restriction or blockage in the air/flue pipe caused by obstructions – Damage The air/flue pipe must be installed in accordance with the recognised rules. If the supply of combustion air (air pipe) or discharge of flue gas (flue pipe) occurs with no problems, clear any faults in the product with and start it up. If F35 occurs again after start-up and the air/flue pipe is present and correct, the function for checking the air/flue pipe can be deactivated via D145. If the function is deactivated via D145, any faults can be cleared in the product and it can be started up. Note D145 can be used to permanently activate or deactivate the function After the function is deactivated, the product no longer automatically checks whether there are restrictions for the air/flue pipe. |
| F42 | Fault: Coding resistor |
Gas family coding resistor short circuit/interruption (on the PCB) – Gas family coding resistor missing – The coding resistor does not match the gas type selection under D.087 Incorrect coding resistor or incorrect gas type selected |
| F49 | Fault: eBUS | Short circuit on eBUS, eBUS overload or two power supplies with different polarities on the eBUS |
| F55 | Fault: CO sensor | Checking the cable harness All-gas sensor defective, replace the all-gas sensor Electronics defective, replace the PCB |
| F56 | Safety switch-off: CO limit exceeded |
Safety shutdown: CO limit value exceeded A component in the combustion regulation is defective – Contact fault at the gas valve assembly (plug not plugged in correctly or not plugged in, plug defective, slot is defective (loose connection)) – If the fault occurs again after being reset: The gas valve assembly is defective |
| F57 | Fault: Measuring program | Active comfort protection mode has detected a regulation fault – Ignition electrode highly corroded |
| F61 | Fault: Fuel valve actuation |
The gas valve assembly cannot be actuated – Cable harness supply line to the gas valve assembly is defective (short to earth, short circuit) – Gas valve assembly defective – PCB defective |
| F62 | Fault: Fuel valve switch-off delay |
Delayed switch-off sequence of gas valve assembly detected – Flame indicator light (ignition and monitoring electrode indicates delayed extinguishing of the flame signal) – Gas valve assembly defective – PCB defective |
| F63 | Fault: EEPROM | Electronics defective |
| F64 | Fault: Electronics/sensor | Flow or return NTC short circuited, electronics defective |
| F65 | Fault: Electronics temp. | Electronics overheating due to external influences, electronics defective |
| F67 | Fault: Electronics/flame | Implausible flame signal, electronics defective |
| F68 | Fault: Flame signal unstable | Air in gas, gas flow pressure too low, incorrect air ratio, condensate route blocked, ionisation flow interruption (cable, electrode), flue gas recirculation, condensate route |
| F70 | Fault: Invalid Device Specific Number | If spare parts fitted: Display and PCB replaced at same time and DSN not reset, incorrect or missing output range coding resistor |
| F71 | Fault: Flow sensor |
Flow temperature sensor signalling constant value: – Flow temperature sensor incorrectly positioned at flow pipe – Flow temperature sensor defective |
| F72 | Fault: Flow/return sensor | Flow/return NTC temperature difference too great → flow and/or return temperature sensor defective |
| F73 | Fault: Water press. sensor | 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 | Fault: Water press. sensor | The line to the water pressure sensor has a short circuit to 5 V/24 V or internal fault in the water pressure sensor |
| F75 | Fault: Pump/ water shortage | Water pressure sensor and/or pump defective, air in the heating installation, insufficient water in the product; connect external expansion vessel to the return |
| F77 | Fault: Flue non-ret. valve/condens. pump | No response from flue non-return flap or condensate pump defective |
| F78 | Interrupt.: DHW outlet sensor on ext. contr. | UK link box is connected but the domestic hot water NTC is not bridged |
| F80 | Fault: actoSTOR inlet sensor | Only in conjunction with F91 NTC defective, NTC cable defective, defective plug connection on NTC, defective plug connection on the actoSTOR electronics Sensor plug has short to earth to the housing, short circuit in cable harness, sensor defective |
| F81 | Fault: cylinder charging pump |
Only in conjunction with F.91 Cylinder is not fully charged after specified time. – Check cylinder charging sensor and cylinder sensor – Air in the actoSTOR pump – Inspect cable harness for pump – Check the impeller sensor and/or limiter in the product – Prioritising diverter valve defective – Secondary heat exchanger blocked – Pump defective |
| F82 | Fault: Ext. current anode |
External current anode not connected: – X43 edge connector with bridge missing from the PCB External current anode connected: – Power supply to the external current anode was interrupted – Cable between PCB and external current anode defective – External current anode defective |
| F83 | Fault: NTC temp. gradient |
When the burner starts, the temperature change registered at the flow and/or return temperature sensor is non-existent or too small. – Insufficient water in product – Flow or return temperature sensor not in correct position at pipe |
| F84 | Fault: NTC temp. diff. 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 installed |
| F85 | Fault: NTCs fitted incorrectly | The flow and/or return temperature sensors have been installed on the same pipe/incorrect pipe |
| F90 | Fault: Communication |
Check the cable harness from the product to the actoSTOR module (PEBus). If the product is to be operated without an actoSTOR module, set D092 = 0. |
| F94 | Fault: Vortex and differential pressure | Check: Pump (function), cable harness, plug, sensors. |
| LED actoSTOR module | actoSTOR electronics status |
LED on: Communication OK LED flashing: Communication not OK LED off: No power supply |
| Communication fault | Communication fault | Communication fault between display and PCB in the electronics box |