Worcester Bosch Boiler Fault Codes

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Worcester Bosch Boiler Fault Codes

If your Worcester Bosch boiler develops a fault, it will automatically enter a lock out mode for safety. It will then display a specific fault code, which will indicate the problem and help to find a solution.

View Bosch Boiler Locking Errors
View Bosch Boiler Blocking Errors

Types of Common Worcester Bosch Fault Errors

Locking Error

The boiler will flash a warning triangle and a fault code, as well as a cause code. You will need to press the reset button on the boiler fascia to clear the fault.

Cause Error

This is a three digit number and will flash on the display during a locking error. During a blocking error, or when the boiler is running smoothly, it won’t be displayed. Instead, it can be accessed on the information menu via the return (or spanner) button.

Fault Error

A number and letter code will showcase the exact fault.

Maintenance Codes

Maintenance codes start with the letter H and are followed by a number, with each code highlighting a situation. These faults do not stop the boiler from working but they do need attention.

  • H11
    How water outlet sensor defect. Hot water can still be delivered, but there’s less control.

  • H13
    A preset time in the service interval function has expired, 1 to 72 months for example. You can set this feature using 2.5F and 0 will disable it.

Blocking Error

The boiler will stop operating without showing any fault data. The cause code displayed in the information menu can be accessed by pressing the return (or spanner) button.

When the fault clears – for example, if the area needs to cool – the blocking error will also clear. Some blocking errors have a designated time before they change to a locking condition.

Worcester Bosch Boiler Locking Errors

9A

HCM (Heat Control Module)

Cause Code – 362

Reset Type – Reset button

Possible Cause – Incorrect HCM fitted

9U

HCM (Heat Control Module)

Cause Code – 233

Reset Type – Reset button

Possible Cause – Problem with the code plug, either faulty or not connected.

B7

Internal Error

Cause Code – 257

Possible Cause – Control board needs replacing.

C6

Fan Problem

Cause Code – 215/216

Reset Type – Reset button

Possible Cause – The fan is running too fast (215) or too slow (216).

C7

Fan Problem

Cause Code – 214

Reset Type – Reset button

Possible Cause – The fan is not running.

C7

No Airflow After a Defined Period of Time

Cause Code – 217

Reset Type – Reset button

Possible Cause – Fan not running or the airflow has been blocked.

D1

Return Sensor Error

Cause Code – 240

Reset Type – Reset button

Possible Cause – The sensor has become wet or damaged, which results in the boiler blocking for 300 seconds beforehand.

D1

Return Sensor Error

Cause Code – 241

Reset Type – Reset button

Possible Cause – The sensor has been disconnected or damaged, which results in the boiler blocking for 300 seconds beforehand.

D1

Return Temperature Too High

Cause Code – 286

Reset Type – Reset button

Possible Cause – Boiler is overheating.

E2

Flow Sensor Short Circuit

Cause code – 222

Reset Type – Reset button

Possible Cause – Flow sensor has become shorted or damaged.

E2

Flow Sensor Open Circuit

Cause Code – 223

Reset Type – Reset button

Possible Cause – Flow sensor has become disconnected or damaged.

E5

Flow Temperature Too High

Cause Code – 218

Reset Type – Reset button

Possible Cause – Primary flow sensor is overheating.

E5

Primary Flow Sensor Has Exceeded 110°C

Cause Code – 332

Reset Type – Reset button

Possible Cause – Primary flow sensor is overheating.

E9

Safety Sensor Temperature Too High

Cause Code – 219

Reset Type – Reset button

Possible Cause – The main heat exchanger has overheated and the maximum temperature has reached 105°C.

E9

Safety Sensor Short Circuit

Cause Code – 220

Reset Type – Reset button

Possible Cause – The maximum temperature sensor on the main heat exchanger has failed.

E9

Safety Sensor Open Circuit

Cause Code – 221

Reset Type – Reset button

Possible Cause – The maximum temperature sensor on the main heat exchanger has not been recognised.

E9

Max Temperature Thermostat Activated

Cause Code – 224

Reset Type – Reset button

Possible Cause – The flue gas thermostat is overheating.

EA

No Flame Detected After Ignition

Cause Code – 227

Reset Type – Reset button

Possible Cause – The ignition has failed four times.

EA

Loss of Flame Signal During Operation

Cause Code – 229

Reset Type – Reset button

Possible Cause – The established flame has been extinguished, which could be due to moisture in the sump or a strong wind into the flue.

EA

Gas Valve Error

Cause Code – 234

Reset Type – Reset button

Possible Cause – The gas valve coil has been disconnected.

EA

Ignition Timing Error

Cause Code – 261

Reset Type – Reset button

Possible Cause – The flame has not been established during the first four seconds of the ignition period.

EA

Too Many Short Burner Starts Without Confirmation

Cause Code – 338

Reset Type – Reset button

Possible Cause – The pump is not detecting water, which can be resolved by checking the pressure gauge and repressurising to one bar.

Worcester Bosch Boiler Blocking Errors

A1

Pump Stuck or Running on Air

Cause Code – 281

Possible Cause – There’s little/no water in the system, which can be resolved by checking the pressure gauge and repressurising to one bar.

C1

Airflow Stopped During Operation

Cause Code – 264

Possible Cause – The fan has stopped working.

EA

No Ionisation Detected After Ignition

Cause Code – 227

Possible Cause – There’s no flame detected, which will lead to the boiler blocking during four attempts before becoming a locking fault.

EF

Central Heating Boiler Defect (large delta T, despite minimum burner)

Cause Code – 349

Possible Cause – The boiler is operating at minimum burner load, whilst there is also a flow and return temperature difference of more than 18°C.

No Code

Safety or Flow Temperature Rises Too Fast

Cause Code – 212

Possible Cause – The air lock or reduced water content has a fault, which can be resolved by checking the pressure gauge and repressurising to one bar.

No Code

The Limit Has Exceeded on the Temperature Difference Between Supply and Return

Cause Code – 213

Possible Cause – The air lock or reduced water content has a fault, which can be resolved by checking the pressure gauge and repressurising to one bar.

No Code

No Temperature Rise After Burner Starts

Cause Code – 260

Possible Cause – The sensor has become disconnected or there’s no water content, which can be resolved by checking the pressure gauge and repressurising to one bar.

Any questions?

If you are looking for a heating engineer within the Milton Keynes area for anything from boiler installations to fixing a tap, or would like some friendly advice please call Mitch directly today on 01908 034194

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