Fault Finding & Diagnosis; Fault Finding - Bosch Worcester GREENSTAR CDi Series Instruction Manual

FAULT FINDING
NOTE: This fault finding information is for guidance only. Worcester Bosch cannot be held responsible for costs incurred by persons not deemed to be
competent.
The electronic control system for this boiler incorporates a blue central indicator. This normally confirms the permanent mains supply but, by flashing dur-
ing a fault, provides a guide to the cause as listed.
This fault finding system assumes that the appliance has been operating normally until the time of failure (i.e. not a first installation error).
PRELIMINARY CHECKS: Preliminary electrical system checks are the first electrical checks to be carried out during a fault-finding procedure.
On completion of the Service/Fault-Finding task which has required the breaking and remaking of electrical connections, check
(a) EARTH CONTINUITY, (b) SHORT CIRCUIT CHECK, (c) POLARITY and (d) RESISTANCE TO EARTH.
An optional text display is avaliable which gives a text description of the service functions of the boiler
Display code Description Remedy
A7 Hot water NTC sensor defective. Check hot water NTC sensor and connecting lead for
circuit breaks/short circuits.
AS Break in communication to TD200 or/and RT10. Check electrical connections.
b1 Code plug not detected. Insert code plug correctly, test and replace if necessary.
C6 Fan speed too low. Check fan lead and connector, and fan; replace as
necessary.
E2 CH flow NTC sensor defective. Check CH flow NTC sensor and connecting lead.
E9 Safety temp. limiter in CH flow has tripped. Check system pressure, check safety temp. limiters,
check pump operation, check fuse on pcb, bleed appli-
ance.
EA Flame not detected. Is gas cock turned on? Check gas supply pressure,
power supply, igniter electrode and lead, ionisation
sensing electrode and lead, flue duct and C02 level.
FO Internal error. Check electrical connector contacts, programmer inter-
face module ignition leads are not loose; replace pcb if
necessary.
F7 Flame detected even though appliance switched off. Check electrode assembly, dry pcb. Flue clear?
FA Flame detected after gas shut off. Check gas valve and wiring to gas valve. Clean conden-
sation trap and check electrode assembly. Flue clear?
Fd Reset button pressed by mistake. Press reset button again.
More detailed fault finding procedures are described in the Service booklet for the Engineer number 6 720 612 361.
FAULT FINDING
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER BOSCH GREENSTAR 25CDI/30CDI/37CDI/42
co;
~ O R C E S T E R
6 720 613 700a (2006/11)
Bosch Group