Listed below are all the Vaillant Ecotec fault codes. These codes help engineers diagnose faults on the Ecotec range quickly, reducing costs and time on a repair job. The code displays on the front of the boiler and overrides any other function of the boiler. If there is more than one fault, the boiler will display each fault code in turn.
Table of Vaillant Ecotec fault codes
We provide links to a number of the faults, simply click on the fault code for more information.
| CODE | MEANING | CAUSE |
| F.0 | Flow-NTC open circuit | NTC broken, NTC cable broken, Defective connection at NTC, Defective connection at electronics |
| F.1 | Return-NTC open circuit | NTC broken, NTC cable broken, Defective connection at NTC, Defective connection at electronics |
| F.10 | Flow NTC short circuit | NTC defective, short circuit in cable harness, cable/casing shortcut |
| F.11 | Return NTC short circuit | NTC defective, short circuit in cable harness, cable/casing shortcut |
| F.13 | Tank NTC short circuit | NTC defective, short circuit in cable harness, cable/casing shortcut |
| F.20 | Safety temperature limiter by NTC activated | Flow-NTC not correctly thermal-connected or defective; appliance does not shut down |
| F.22 | Dry fire | Too little water in the appliance, water pressure sensor defective, cable to pump or water sensor defective, pump blocked or defective, pump output too low |
| F.23 | Water shortage, temperature difference between flow and return NTC too large | Pump blocked or defective, pump output too low, flow and return NTC interchanged |
| F.24 | Water shortage, temperature rise too quick | Pump blocked, insufficient pump output, air in appliance, water pressure too low |
| F.25 | Interruption in the compact thermal module cable harness | Compact thermal module cable harness defective |
| F.27 | Incorrect sensing of flame | Flame detector defective |
| F.28 | Appliance does not start: Attempts to ignite during start failed | Faults in gas supply such as: Gas meter or gas pressure defective; Air in gas; Gas flow pressure too low; Fire protection tap has disengaged. Faults in the gas valve, wrong gas setting, igniter (ignition transformer, ignition cable, ignition plug) defective, ionisation current stopped (cable, electrode), faulty earthing in appliance, electronics defective |
| F.29 | Flame goes off during operation and subsequent ignition attempts failed | Gas supply temporarily stopped, faulty earthing of appliance |
| F.32 | Fan speed variation | Fan blocked, plug not inserted correctly on fan, hall sensor defective, fault in cable harness, electronics defective |
| F.49 | eBUS undervoltage | Short circuit on eBUS, overload on eBUS or two power sources on eBUS with different polarity |
| F.61 | Gas-valve control defective | Short circuit/earth (ground) leak in cable harness to gas valve, gas valve assembly defective (earth/ground leak from coils), electronic control system defective |
| F.62 | Gas valve shutoff delay | Gas valve leaking, electronics defective |
| F.63 | EEPROM error | Electronics defective |
| F.64 | Electronics/NTC fault | Short-circuit in flow or return NTC or electronics defective |
| F.65 | Electronics temperature too high | Electronics too hot due to external effect, electronics defective |
| F.67 | Flame detector input signal outside the limits (0 or 5V) | Electronics defective |
| F.70 | No valid DSN in display and/or main board | Spare part failure display and mainboard interchanged at the same time and device specific number not adjusted |
| F.71 | Flow NTC reports constant value (stuck at) | Flow NTC is defective |
| F.72 | Flow and/or return NTC fault | Flow and/or return NTC is defective (tolerances too big) |
| F.73 | Water pressure sensor signal out of range (too low) | Cable to water pressure sensor is broken or has a short-circuit at 0V or water pressure sensor defective |
| F.74 | Water pressure sensor signal out of range (too high) | Cable to water pressure sensor has a short-circuit at 5V/24V or internal fault in water pressure sensor |
| F.75 | No pressure rise was detected on turning on the pump | Water pressure sensor or/and pump defective. Air in the heating system, quickness’s bleeder defective. Too little water in appliance; check adjustable by-pass; connect expansion vessel to return |
| F.76 | Overheating protection on primary heat exchanger triggered | Cable or cable connection of fuse in the primary heat exchanger defective, or primary heat exchanger defective |
| F.77 | Condensate pump or feedback of accessories blocks heating | Condensate pump defective or flume flap feedback triggered |
This Vaillant Ecotec fault codes guide is designed to help you understand what might be wrong with your Vaillant Ecotec boiler. In most cases it will require a Gas Safe Qualified Engineer to rectify the issue, and new parts may be required.