Worcester Bosch Heat Pump Error Codes

Complete diagnostic guide for Worcester Bosch heat pumps in the United Kingdom.

Sensor and Flow Errors

Error codes for Worcester Bosch heat pumps related to sensor, flow and temperature measurement problems.

Error Code	Meaning	Possible Causes	Solutions
D1	Sensor is wet, damaged or disconnected	Sensor has become wet Sensor damaged or defective Sensor not properly connected Cable connection interrupted Short circuit in wiring	Check sensor for moisture and dry if necessary Inspect sensor for visible damage Check wiring for proper connection Check connectors for corrosion or loose contacts Test sensor with multimeter Replace sensor if defective Restart system after repair
E2	Flow sensor is short-circuited, damaged or disconnected	Flow sensor short-circuited Sensor damaged or defective Sensor not properly connected Cable connection interrupted Contaminated or blocked sensor	Check flow sensor for contamination and clean Check wiring for damage and proper connection Test sensor with multimeter Check connectors for corrosion Replace flow sensor if defective Restart system after repair
E5	Primary flow sensor has overheated	System temperature too high Insufficient flow Blocked or contaminated heat exchanger Defective flow sensor Pump problems	Check system temperature and reduce if necessary Check flow rate in system Check heat exchanger for blockages or contamination Test pump function Bleed system Contact qualified service if problem persists

Overheating Errors

Error codes for Worcester Bosch heat pumps related to overheating problems.

Error Code	Meaning	Possible Causes	Solutions
E9	Main heat exchanger has overheated	Insufficient flow through heat exchanger Contaminated or blocked heat exchanger System temperature too high Defective pump Air in system	Check heat exchanger for contamination or blockages and clean Increase flow rate in system Bleed system completely Test pump function Check system temperature and reduce if necessary Contact qualified service if problem persists
EA	Flue thermostat has overheated or boiler could not ignite	Flue thermostat detected overheating Boiler could not ignite after four attempts Contaminated burner Problems with gas supply Defective igniter	Allow system to cool down Check burner for contamination and clean Check gas supply Test igniter function Check flue thermostat Contact qualified service if problem persists

Fan and System Errors

Error codes for Worcester Bosch heat pumps related to fan and system control problems.

Error Code	Meaning	Possible Causes	Solutions
C7	Fan not running or airflow blocked	Fan not running Airflow blocked Fan motor defective Fan wiring damaged Contaminated or blocked fan blades	Check air duct for obstructions or blockages Check fan blades for contamination and clean Check fan wiring for damage Test fan motor function Check connectors for proper connection Replace fan or motor if defective Restart system after repair
C6	System running too fast or too slow	Incorrect system settings Defective control board Problems with pump control Incorrect parameter configuration	Check and correct system settings Check pump control Check parameter configuration Check control board for errors Reset system if necessary Contact qualified service for diagnosis

Control and Hardware Errors

Error codes for Worcester Bosch heat pumps related to control board and hardware component problems.

Error Code	Meaning	Possible Causes	Solutions
9A	Incorrect Heat Control Module (HTM) installed	Incorrect Heat Control Module installed Incompatible hardware Incorrect module configuration Compatibility problems	Check installed HTM for compatibility with device type Install correct Heat Control Module Check module configuration Check firmware version Contact qualified service if uncertain
9U	Faulty or incorrectly connected code plug	Code plug faulty Code plug not correctly connected Damaged connector Incorrect code plug installed	Check code plug for proper connection Inspect connector for damage Check code plug for compatibility Replace code plug if defective Restart system after repair
B7	Control board must be replaced	Control board defective Hardware error on board Electronic components damaged Board not compatible	Check control board for visible damage Check board for compatibility with device type Have control board replaced by qualified service Reconfigure system after replacement Contact qualified service for diagnosis and repair

Need More Help?

If you are experiencing problems with your Worcester Bosch heat pump that are not covered by these error codes, or if the provided solutions do not resolve your issue, we recommend:

Consult your Worcester Bosch heat pump user manual for model-specific information
Contact Worcester Bosch customer service in the United Kingdom for technical support
Seek help from a qualified heat pump repair technician
Check warranty coverage if your heat pump is still under warranty

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