Fault Modes; Error Codes - Keston Qudos 28s User, Installation And Servicing Instructions

WD420/3/2007
6.3

FAULT MODES

If a situation is detected which the boiler considers may cause damage to the appliance the boiler
will enter a lockout mode and stop functioning. After clearing the problem the user must also press
the "Reset" button once to resume boiler operation in most circumstances. However, certain
faults, as designated "Service Reset Required" in the table below, will not reset from the fascia
button. These require the Service Reset button on the main PCB (see Fig 6.5) to be pressed. IN
BOTH TYPES OF LOCKOUT, TURNING THE POWER ON THEN OFF WILL NOT CLEAR A
LOCKOUT SITUATION

ERROR CODES

Display Description of fault
E01 Flame sequence lockout - possible board or electrical supply fault.
E02 Ignition failure. Boiler made made five unsuccessful attempts to ignite. Check
gas supply, ignitor condition and spark gap. Check flue and air system and
condensate drainage for obstruction. Check gas valve setting and operation
E03 Spark gap too small OR Gas valve faulty - check connections to gas valve and
operation of gas valve solenoids
E04 Flame lost 5 times in a single demand period - check combustion setting high
and low, and ignitor condition
E12 Flow overheat - check water circulation is not blocked, check pump operation
and flow thermistor condition.
E20 Fan unable to reach ignition rate -check fan and impellar restriction
E24 Return exceed flow temperature by 10C - check direction of water circulation and
operation of flow and return thermistors
E25 Flow temperature increased too quickly - check water circulation and pump
operation
E26 Water pressure sensor is open circuit/disconnected
E28 Fan fault - check connector to fan operation of fan
E31 Flow thermistor closed circuit - check the connections and wires to the flow
thermistor are intact not short circuited
E32 Return thermistor closed circuit - check the connections and wires to the return
thermistor are intact not short circuited
E33 DHW thermistor closed circuit - check the connections and wires to the DHW
thermistor are intact not short circuited, if present
E35 Flue thermistor closed circuit - check the connections and wires to the flue
thermistor are intact not short circuited
E36 Flow thermistor open circuit/not connected - check the connections and wires to
the flow thermistor are intact and connected
E37 Return thermistor open circuit/not connected - check the connections and wires
to the return thermistor are intact and connected
E38 DHW thermistor open circuit/not connected - check the connections and wires to
the DHW thermistor are intact and connected, if present
E40 Flue thermistor open circuit/not connected - check the connections and wires to
the flue thermistor are intact and connected - SERVICE RESET REQUIRED
E52 Flue overheat - check combustion and heat exchanger. Reset required on main
PCB - SERVICE RESET REQUIRED
E62 Water pressure is > 2,7 bar - check operation of expansion vessel or filling loop
is left open
E67 Water pressure is < 0.4bar
E70 Cabinet overheat - thermal fuse will need replacing. Check hot gasket joints and
combustion for cause of overheat. Reset required on main PCB - SERVICE
RESET REQUIRED
E73 Code plug error - check loom and connections to main pcb.
E74 Supply voltage < 190V - check mains supply condition
E75 Supply voltage > 270V - check mains supply condition
E76 Solar panel sensor closed circuit - if present.
E77 Solar panel sensor open circuit - if present
E95 Solar tank sensor closed circuit - if present
E96 Solar tank sensor open circuit - if present
Installation & Servicing Instructions
Chapter 6 : Fault Finding The Keston Qudos 28s & Qudos 28sP Boilers
Page : 33