Worcester Bosch Fault Code A7

Welcome to the fault-codes section of this site. The following table or page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. You may be guided through the fault finding sequence or steps, for rectifying your boiler with this fault code. Suggested repair solutions may be provided by a link to a repair page. NB Some fault codes are only applicable to a specific range of boilers only.

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.

Step	Check		Action
1.	▶ Check if the water NTC connector corroded, damaged or dirty.	yes:	▶ Change relative parts. A7? go to step 2
		no:	go to step 2
2.	▶ Switch OFF the appliance. ▶ Disconnect the boiler power connection. ▶ Un-plug 20-pin connector from PCB. ▶ Check resistance from connections 3 to 4 on the cable side. Does the value match the ones described in table 39, page 36?	yes:	▶ Connect the boiler electrical connection. ▶ Switch ON the appliance. ▶ Make a note of the altered service function settings (see table 4 on page 6) in order to keep the altered values. ▶ Switch OFF the appliance. ▶ Disconnect the boiler power connection. ▶ Change PCB control board. ▶ Reconnect the appliance power connection. ▶ Switch ON the appliance. ▶ Restore service settings previously noted.
		no:	go to step 3
3.	▶ Un-plug NTC sensor from cable. ▶ Check resistance of NTC sensor. Does the value match the ones described in table 39, page 36?	yes:	▶ Change the 20-pin connector lead assembly. ▶ Reconnect the boiler electrical connection. ▶ Switch ON the appliance.
		no:	▶ Change NTC sensor. ▶ Reconnect the boiler electrical connection. ▶ Switch ON the appliance.