FAULT FINDING AND DIAGNOSIS
6 720 803 800 (2012/11)
68
BLOCKING ERRORS
F0
237
Internal error
Call Worcester, Bosch Group
Technical helpline 0844 892 3366
238
Gas valve error
Reset button
Leaking gas valve
239
242 - 256
258
259
262
263
267
272
279
290
Internal error
Call Worcester, Bosch Group
Technical helpline 0844 892 3366
278
Sensor test failed
Reset button
On power up all safety sensors are checked.
Check has failed.
280
Recycle time error
Reset button
After the burner has stopped, the recycle mode purges gas from the
heat exchanger before attempting to burn again. The software has 3.1
seconds to intervene before the boiler goes into this fault condition.
338
Too many short burner starts
without confirmation
Reset button
There is an error where the pump is not detecting water.
F7
228
Flame error
Reset button
False flame. Flame detected before burner start.
328
Internal error
Replace control board
FA
306
False flame error
Reset button
Flame detected after burner stop
FD
231
Mains power error
Reset button
Electrical power interruption.
FA
364
Gas valve EV2 leak test failed
Reset button
Gas valve leak.
Fb
365
Gas valve EV1 leak test failed
Reset button
Gas valve leak.
Fault
code
Cause
code
Description
Possible cause
A1
281
Pump stuck or running in air
Little or no water in the system.
C1
264
Airflow stopped during operation
Fan has stopped.
C4
273
Airflow present during last 24 hours
Fan has been running continuously during the past 24 hours.
D1
240
Return sensor short circuit
Wet sensor.
Blocking for 300 secs before going to Locking error (
table 21).
241
Return sensor disconnected
Blocking for 300 secs before going to Locking error (
table 21).
D4
271
Temperature difference between flow and
safety sensors exceeds limit
The temperature of the primary flow and the safety sensor on the WB7 should
be within 15°C of each other.
Table 22 Blocking codes
Fault codes
Cause
codes
Description
Reset type
Possible cause
Table 21 Locking fault and cause code listing
