Worcester Bosch Fault Code E9

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.

E9 and button reset and fault indicator LED are flashing. Safety temperature circuit has tripped.

Step	Check		Action
1.	Type of CH system: Is the appliance installed in a fully pumped sealed system?	yes:	go to step 3
		no:	go to step 2
2.	Open vented CH system: Is there enough water in the feed and expansion tank?	yes:	go to step 4
		no:	▶ Top up system. ▶ Vent appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 4
3.	Fully pumped sealed systems: Is the heating pressure between 1 and 2 bar?	yes:	go to step 4
		no:	▶ Top up system. ▶ Vent appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 4
4.	Is the pump seized?	yes:	▶ Free/release the pump. If pump won’t start: ▶ Switch OFF the appliance. ▶ Disconnect the boiler power connection. ▶ Drain appliance. ▶ Change the pump (see Installation Instructions). ▶ Fill system, vent and re-pressurise (see installation instructions). ▶ Reconnect the appliance power connection. ▶ Switch ON the appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 5
		no:	go to step 5
5.	Lead disconnected from flue safety temperature limiter and/or CH flow safety temperature limiter?	yes:	▶ Switch OFF the appliance. ▶ Reconnect lead. ▶ Switch ON the appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 4
		no:	go to step 4
6.	▶ Switch OFF the appliance. ▶ Un-plug the connector from the flue safety temperature limiter. ▶ Measure the flue safety temperature limiter for continuity. Resistance small?	yes:	▶ Connect flue gas safety temperature limiter lead. go to step 5
		no:	▶ Change the flue safety temperature limiter. ▶ Connect flue gas safety temperature limiter lead. ▶ Switch ON the appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 5
7.	▶ Disconnect lead to CH flow safety temperature limiter. ▶ Measure the CH flow safety temperature limiter for continuity. Resistance small?	yes:	▶ Connect CH flow safety temperature limiter. go to step 6
		no:	▶ Change CH flow safety temperature limiter. ▶ Connect CH flow safety temperature limiter. ▶ Switch ON the appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 6
8.	▶ Disconnect the boiler power connection. ▶ Unplug connector of harness that connects the limiters to PCB from control board. Test harness (including the two limiters) for continuity. Resistance small?	yes:	▶ Reconnect connector. go to step 7
		no:	Harness defective. ▶ Repair or replace the harness. ▶ Reconnect the appliance power connection. ▶ Switch ON the appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 7
9.	▶ Disconnect the boiler power connection. ▶ Remove fuse SI 3 from appliance PCB control board and test for continuity. Is there continuity?	yes:	▶ Remount the fuse. ▶ Reconnect the appliance power connection. ▶ Switch ON the appliance. go to step 8
		no:	▶ Change the fuse. ▶ Reconnect the appliance power connection. ▶ Switch ON the appliance. ▶ Press the reset button for 3 seconds and release it. After releasing the appliance re-starts. E9? go to step 8
10.	The PCB is damaged.		▶ Make a note of the altered service settings. ▶ 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 down.