Vaillant ecoTEC plus 937 Instructions And Maintenance Instructions - page 50
Installation and maintenance instructions ecoTEC plus 0020031552_03
50
Code
Meaning
Cause
F.0
Flow NTC open circuit
NTC faulty, NTC cable faulty, faulty plug connection on NTC,
faulty plug connection on the electronics
F.01
Return NTC open circuit
NTC faulty, NTC cable faulty, faulty plug connection on NTC,
faulty plug connection on the electronics
F.02
Shift load storage tank charging (NTC) open circuit,
only in combination with F.91
NTC faulty, NTC cable faulty, faulty plug connection on NTC,
faulty plug connection on the electronics
F.03
Shift load storage tank temperature (NTC) open circuit,
only in combination with F.91
NTC faulty, NTC cable faulty, faulty plug connection on NTC,
faulty plug connection on the electronics
F.10
Flow NTC short circuit
NTC faulty, NTC plug short-circuited to casing
F.11
Return NTC short circuit
NTC faulty, NTC plug short-circuited to casing
F.12
Short circuit in storage tank charging sensor (NTC)
only in combination with F.91
Sensor plug has mass short to the casing, short-circuit in wiring
loom, sensor faulty
F.13
Short circuit storage tank temperature sensor (NTC)
only in combination with F.91
Sensor plug has mass short to the casing, short-circuit in wiring
loom, sensor faulty
F.20
Safety temperature limiter by NTC activated
Flow probe not connected thermally correct or defective, appli-
ance does not shut down
F.22
Dry fire
Too little water in the appliance, water pressure sensor defec-
tive, cable to pump or water pressure sensor defective, pump
seized or defective, pump output too low
F.23
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
F.24
Water shortage, temperature rise too quick
Pump seized, low output from the pump, air in appliance, system
pressure too low
F.25
Compact thermal module wiring harness open circuit
Wiring harness thermo-compact module faulty
F.27
Incorrect sensing of flame
Flame monitor faulty
F.28
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 trans-
former, ignition cable, ignition plug) defective, ionisation current
stopped (cable, electrode), faulty earthing in appliance, electro-
nics defective
F.29
Flame goes off during operation and subsequent ignition
attempts failed
Gas supply temporarily interrupted, defective earthing of the unit
F.32
Speed deviation Fan
Fans seized, plug not inserted correctly on fan, hall sensor de-
fective, fault in cable harness, electronics defective
F.49
eBUS undervoltage
Short-circuit on eBUS input, eBUS overload or two power sup-
plies with different polarities on the eBUS
F.61
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.
F.62
Switch-off delay of the gas valve faulty
gas valve leaking, electronics defective
F.63
EEPROM error
Defective electronics
F.64
Electronics/NTC fault
Short-circuit in flow or return NTC or electronics defective/ air
in gas
F.65
Electronics temperature too high
Electronics too hot due to external effect, electronics defective
F.67
Flame monitor input signal is outside the limits (0 or 5 V)
electronics defective
F.70
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
F.71
Flow NTC reports constant value
Flow NTC is defective
F.72
Flow and/or return NTC fault
Feed and/or return NTC is faulty (tolerance too great)
F.73
Signal water pressure sensor in the wrong range
(too low)
Line to water pressure sensor is interrupted or has a short-cir-
cuit to 0 V or water pressure sensor faulty
F.74
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
F.75
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;
F.76
Overheating protection on primary heat-exchanger
activated
Cable or cable connection of fuse in the primary heat exchanger
defective, replace primary heat exchanger
F.77
Condensate pump or return signal from accessory
module blocks heating
Condensate pump faulty or return signal from the exhaust gas
flap has activated
F.78
Incorrect configuration of accessories
Control Center VR 65 connected to combination boiler
F.80
Interruption or short-circuit of SWT inlet sensor only in
conjunction with F.91
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
Table 8.4 Error codes
8 Troubleshooting