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boiler service, boiler repair, emergency repair
Vaillant Ecotec plus 937 Boiler Fault Codes
| Code | Meaning | Cause |
| F0 | Flow NTC open circuit | NTC faulty, NTC cable faulty, faulty plug connection on NTC, faulty plug connection on the electronics |
| F01 | Return NTC open circuit | NTC faulty, NTC cable faulty, faulty plug connection on NTC, faulty plug connection on the electronics |
| F02 | Shift load storage tank charging (NTC) open circuit, only in combination with F91 | NTC faulty, NTC cable faulty, faulty plug connection on NTC, faulty plug connection on the electronics |
| F03 | Shift load storage tank temperature (NTC) open circuit, only in combination with F91 | NTC faulty, NTC cable faulty, faulty plug connection on NTC, faulty plug connection on the electronics |
| F10 | Flow NTC short circuit | NTC faulty, NTC plug short-circuited to casing |
| F11 | Return NTC short circuit | NTC faulty, NTC plug short-circuited to casing |
| F12 | Short circuit in storage tank charging sensor (NTC) only in combination with F91 | Sensor plug has mass short to the casing, short-circuit in wiring loom, sensor faulty |
| F13 | Short circuit storage tank temperature sensor (NTC) only in combination with F91 | Sensor plug has mass short to the casing, short-circuit in wiring loom, sensor faulty |
| F20 | Safety temperature limiter by NTC activated | Flow probe not connected thermally correct or defective, appliance does not shut down |
| F22 | Dry fire | Too little water in the appliance, water pressure sensor defective, cable to pump or water pressure sensor defective, pump seized or defective, pump output too low |
| F23 | Water shortage, temperature spread between flow and return NTC too large | Pump seized or defective, pump output too low, flow and return sensor swapped over |
| F24 | Water shortage, temperature rise too quick | Pump seized, low output from the pump, air in appliance, system pressure too low |
| F25 | Compact thermal module wiring harness open circuit | Wiring harness thermo-compact module faulty |
| F27 | Incorrect sensing of flame | Flame monitor faulty |
| F28 | Unit will not start: Attempts to ignite during start failed |
Faults in the gas supply such as: - Gas meter or gas pressure regulator - Air in gas - Gas flow pressure too low 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 |
| F29 | Flame goes off during operation and subsequent ignition attempts failed | Gas supply temporarily interrupted, defective earthing of the unit |
| F32 | Speed deviation Fan | Fans seized, plug not inserted correctly on fan, hall sensor defective, fault in cable harness, electronics defective |
| F49 | eBUS undervoltage | Short-circuit on eBUS input, eBUS overload or two power supplies with different polarities on the eBUS |
| F61 | Gas valve control faulty | Short circuit/earth(ground) leak in cable harness to gas valve, gas valve assembly defective (earth/ground leak from solenoid), electronics fault. |
| F62 | Switch-off delay of the gas valve faulty | gas valve leaking, electronics defective |
| F63 | EEPROM error | Defective electronics |
| F64 | Electronics/NTC fault | Short-circuit in flow or return NTC or electronics defective/ air in gas |
| F65 | Electronics temperature too high | Electronics too hot due to external effect, electronics defective |
| F67 | Flame monitor input signal is outside the limits (0 or 5 V) | Electronics defective |
| F70 | No valid appliance variant for display and/or electronics (DSN number invalid) | Spare parts error: Display and electronics changed at the same time appliance variant not re-set |
| F71 | Flow NTC reports constant value | Flow NTC is defective |
| F72 | Flow and/or return NTC fault | Feed and/or return NTC is faulty (tolerance too great) |
| F73 | Signal water pressure sensor in the wrong range (too low) | Line to water pressure sensor is interrupted or has a short-circuit to 0 V or water pressure sensor faulty |
| F74 | Signal water pressure sensor in the wrong range (too high) | Harness to water pressure sensor has a short-circuit at 5 V / 24 V or internal fault in water pressure sensor |
| F75 | No sudden change in pressure was detected on turning on the pump |
Water pressure sensor and/or pump faulty (pump seized - check system water for contamination) Air in heating system, automatic air vent system faulty Too little water in the unit; check adjustable bypass; Connect expansion vessel in return; |
| F76 | Overheating protection on primary heat-exchanger activated | Cable or cable connection of fuse in the primary heat exchanger defective, replace primary heat exchanger |
| F77 | Condensate pump or return signal from accessory module blocks heating | Condensate pump faulty or return signal from the exhaust gas flap has activated |
| F78 | Incorrect configuration of accessories | Control Center VR 65 connected to combination boiler |
| F80 | Interruption or short-circuit of SWT inlet sensor only in conjunction with F91 |
NTC defective, NTC cable defective, defective plug connection at NTC, defective plug connection at APC electronics Plug at sensor has short-circuited to housing, short-circuit in cable harness, sensor defective |
| F81 | APC loadpump fault connected to F91 |
Inadequate heat transfer between the heater and storage tank. – Check storage tank charge sensor and storage tank sensor – Air in the APC pump – Check pump wiring harness – Secondary heat exchanger blocked – Priority changeover valve defective – Pump defective – Plate-type heat exchanger scaled |
| F90 | Communication with shift load storage tank module interrupted | Check wiring harness from combi boiler to shift load storage tank (PE Bus). If combi boiler is to be operated without shift load storage tank, set d.92 = 0 |
| F91 | Sensor error on shift load storage tank module (NTC) | NTC faulty, NTC cable faulty, faulty plug connection on NTC, faulty plug connection on the electronics |
| con | No communication with the printed circuit board | Communication fault between the display and the printed circuit board in the electronics box |