Worcester CDi Combi N.G Service Booklet page 32

RECTIFYING FAULTS
A7
and fault indicator LED are flashing.
(Boiler still produces hot water but at a lesser degree of accuracy over the temperature.)
Water NTC sensor defective.
Check
1. B Check if the water NTC connector
corroded, damaged or dirty.
2. B Switch OFF the appliance.
B Disconnect the boiler power
connection.
B Un-plug 20-pin connector from
PCB.
B Check resistance from
connections 3 to 4 on the cable
side. Does the value match the
ones described in table 38,
page 71?
3. B Un-plug NTC sensor from cable.
B Check resistance of NTC sensor.
Does the value match the ones
described in table 38, page 71?
Tab. 16 A7 Error codes
32
Supplied By www.heating spares.co Tel. 0161 620 6677
Action
yes: B Change relative parts.
A7? go to 2
no: go to 2
yes: B Connect the boiler electrical connection.
B Switch ON the appliance.
B Make a note of the altered service function
settings (see table 6 on page 18) in order to keep
the altered values.
B Switch OFF the appliance.
B Disconnect the boiler power connection.
B Change PCB control board.
B Reconnect the appliance power connection.
B Switch ON the appliance.
B Restore service settings previously noted.
no: go to 3
yes: B Change the 20-pin connector lead assembly.
B Reconnect the boiler electrical connection.
B Switch ON the appliance.
no: B Change NTC sensor.
B Reconnect the boiler electrical connection.
B Switch ON the appliance.
8 716 115 748 (2009/09)