10
Troubleshooting
Logano plus GB312 – 6 720 806 273 (2013/01)
54
V
4U
522
Short-circuit between boiler
temperature sensors 1 and
2.
A temperature sensor
fault was detected in test
mode.
Check sensor lead.
Check connector.
Check sensor readings
against sensor
characteristic.
Check the voltage at the
temperature sensor
against the table (SAFe
documentation).
Replace if damaged.
If dirty, clean or replace
as necessary.
If connector is loose,
reconnect properly.
Replace temperature
sensor if there are
discrepancies.
Replace SAFe if there
are discrepancies.
V
4Y
523
Circuit break on supply
temperature sensor.
Temperature at supply
temperature sensor.
< 23 °F (< -5 °C)
Check sensor lead.
Check connector.
Check sensor readings
against sensor
characteristic.
Check the voltage at the
temperature sensor
against the table (SAFe
documentation).
Replace if damaged.
If dirty, clean or replace
as necessary.
If connector is loose,
reconnect properly.
Replace temperature
sensor if there are
discrepancies.
Replace SAFe if there
are discrepancies.
V
4U
524
Flow temperature sensor
short-circuit.
Current supply
temperature
> 266 °F (> 130 °C)
Check sensor lead.
Check connector.
Check sensor readings
against sensor
characteristic.
Check the voltage at the
temperature sensor
against the table (SAFe
documentation).
Replace if damaged.
If dirty, clean or replace
as necessary.
If connector is loose,
reconnect properly.
Replace temperature
sensor if there are
discrepancies.
Replace SAFe if there
are discrepancies.
V
4A
575
STB response.
The boiler supply
temperature has
reached its maximum
permissible value.
High temperature safety
cut-out has tripped.
Check gas valve.
K
5L
542
Incomplete communication
with SAFe.
The MC10 registers this
fault if not all required
data is supplied by the
SAFe.
Check wiring connections
between SAFe and
MC10.
If connections OK,
replace SAFe
Type
1)
Display code Fault code
Cause
Description
Testing sequence/
Cause
Measure
Table 23 Fault displays
1) V = interlocking; B = inhibiting; BC = operating code
