Vaillant Ecotec fault codes to help diagnostics and repairs

Vaillant Ecotec fault codes

Listed are the Vaillant Ecotec fault codes with links to help pages if you experience a lockout on your boiler.

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.

CODEMEANINGCAUSE
F.0Flow-NTC open circuitNTC broken, NTC cable broken, Defective connection at NTC, Defective connection at electronics
F.1Return-NTC open circuitNTC broken, NTC cable broken, Defective connection at NTC, Defective connection at electronics
F.10Flow NTC short circuitNTC defective, short circuit in cable harness, cable/casing shortcut
F.11Return NTC short circuitNTC defective, short circuit in cable harness, cable/casing shortcut
F.13Tank NTC short circuitNTC defective, short circuit in cable harness, cable/casing shortcut
F.20Safety temperature limiter by NTC activatedFlow-NTC not correctly thermal-connected or defective; appliance does not shut down
F.22Dry fireToo 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.23Water shortage, temperature difference between flow and return NTC loo largePump blocked or defective, pump output too low, flow and return NTC interchanged
F.24Water shortage, temperature rise too quickPump blocked, insufficient pump output, air in appliance, water pressure too low
F.25Interruption in the compact thermal module cable harnessCompact thermal module cable harness defective
F.27Incorrect sensing of flameFlame detector defective
F.28Appliance does not start: Attempts to ignite during start failedFaults 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.29Flame goes off during operation and subsequent ignition attempts failedGas supply temporarily stopped, faulty earthing of appliance
F.32Fan speed variationFan blocked, plug not inserted correctly on fan, hall sensor defective, fault in cable harness, electronics defective
F.49eBUS undervoltageShort circuit on eBUS, overload on eBUS or two power sources on eBUS with different polarity
F.61Gas-valve control defectiveShort circuit/earth (ground) leak in cable harness to gas valve, gas valve assembly defective (earth/ground leak from coils), electronic control system defective
F.62Gas valve shutoff delayGas valve leaking, electronics defective
F.63EEPROM errorElectronics defective
F.64Electronics/NTC faultShort-circuit in flow or return NTC or electronics defective
F.65Electronics temperature too highElectronics too hot due to external effect, electronics defective
F.67Flame detector input signal outside the limits (0 or 5V)Electronics defective
F.70No valid DSN in display and/or main boardSpare part failure display and mainboard interchanged at the same time and device specific number not adjusted
F.71Flow NTC reports constant value (stuck at)Flow NTC is defective
F.72Flow and/or return NTC faultFlow and/or return NTC is defective (tolerances too big)
F.73Water 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.74Water 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.75No pressure rise was detected on turning on the pumpWater 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.76Overheating protection on primary heat exchanger triggeredCable or cable connection of fuse in the primary heat exchanger defective, or primary heat exchanger defective
F.77Condensate pump or feedback of accessories blocks heatingCondensate 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.

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