Short answer
Hamworthy boilers with Siemens LMS controls (Wessex ModuMax mk3 and mk4, Purewell VariHeat mk2, Stratton mk2, Upton and Varmax) share one numeric fault list. Key codes: 133 — safety time for flame establishment exceeded; 128 — flame lost during operation; 132 — safety shutdown; 110/111 — limit thermostat; 118 — water pressure too low; 153 — unit manually locked; 160 — fan speed not reached; 164 — flow/pressure switch error.
Reading the code
Hamworthy advises entering LMS codes as numbers only, without letters. So 'E133' on the display is code 133. Where an internal code is also shown, quote both when you call for help.
Common causes on site
133 and 128 are the classic ignition and flame faults: check gas inlet pressure with the cascade at full fire, the ionisation probe and its lead, condensate trap and flue. 132 is a general safety shutdown — gas pressure, flue and condensate blockage and safety switches. 153 simply means reset was pressed with no fault present, or held too long. 164 and 118 are water side, not gas side.
Before you reset
A single reset after a power cut or a known one-off event is reasonable. Repeated resets are not: many commercial controls count resets and lock out further (for example a 'too many resets' code), and resetting a flame or gas valve fault over and over can mask a dangerous condition. If a lockout returns, isolate the appliance and call a Gas Safe registered engineer with the relevant commercial competence.
Hamworthy LMS control fault codes
| Code | Meaning | What to check |
|---|---|---|
| 10 | Outside temperature sensor error | Check connection, check sensor, check cable |
| 20 | Boiler temperature 1 sensor error | Check connection, check sensor, check cable |
| 25 | Boiler temperature solid fuel sensor error | Check connection, check sensor, check cable |
| 26 | Common flow temperature sensor error | Check connection, check sensor, check cable |
| 28 | Flue gas temperature sensor fault | Check connection, check sensor, check cable |
| 30 | Flow temperature 1 sensor error | Check connection, check sensor, check cable |
| 31 | Flow temperature 1 cooling sensor error | Check connection, check sensor, check cable |
| 32 | Flow temperature 2 sensor error | Check connection, check sensor, check cable |
| 38 | Flow temperature primary controller | Check connection, check sensor, check cable |
| 40 | Return temperature 1 sensor error | Check connection, check sensor, check cable |
| 46 | Cascade return temperature sensor error | Check connection, check sensor, check cable |
| 47 | Common return temperature sensor error | Check connection, check sensor, check cable |
| 50 | DHW temperature sensor/thermostat 1 fault | Check connection, check sensor, check cable |
| 52 | DHW temperature sensor/thermostat 2 fault | Check connection, check sensor, check cable |
| 54 | Flow temperature DHW | Check connection, check sensor, check cable |
| 57 | DHW | Check connection, check sensor, check cable |
| 60 | Room temperature 1, sensor error | Check connection, check sensor, check cable |
| 61 | Fault room unit 1 | Check room device. |
| 65 | Room temperature 2 | Check connection, check sensor, check cable |
| 68 | Room temperature 3 | Check connection, check sensor, check cable |
| 70 | Storage tank temperature 1 (top) | Check connection, check sensor, check cable |
| 71 | Storage tank temperature 2 (bottom) | Check connection, check sensor, check cable |
| 72 | Storage tank temperature 3 (middle) | Check connection, check sensor, check cable |
| 73 | Collector temperature 1 | Check connection, check sensor, check cable |
| 74 | Collector temperature 2 sensor error | Check connection, check sensor, check cable |
| 78 | Water pressure | Check connection, check sensor, check cable |
| 81 | LPB short-circuit or no bus power supply | Check wiring, check polarity |
| 82 | LPB address collision | Check connection, check address |
| 83 | BSB-Wire short-circuit or no communication | Check wiring, check polarity |
| 84 | BSB wire address collision | Check wiring, check polarity |
| 85 | BSB radio communication fault | Connect compatible room control unit. Check wireless communication. |
| 91 | Data overrun in EEPROM | Contact Hamworthy Heating. |
| 98 | Mixing valve clip in 1 fault | Check wiring, check polarity |
| 99 | Mixing valve clip in 2 fault | Check wiring, check polarity |
| 100 | Two clock time masters | Check parameter setting. |
| 102 | Clock time master without power reserve | Check wiring, check polarity |
| 105 | Maintenance message | Reset in parameters. |
| 109 | Supervision boiler temperature | Allow the boiler to cool, investigate cause of overheating. |
| 110 | SLT lockout | Allow the boiler to cool and reset thermostat, investigate cause of overheating. |
| 111 | Temperature limiter safety shutdown | Allow the boiler to cool and reset thermostat, investigate cause of overheating. |
| 113 | Flue gas supervision equipment has cut out | Check the cause of high flue gas temperature. Check sensor. |
| 117 | Water pressure too high | Check system pressure, check water pressure sensor. |
| 118 | Water pressure too low 6 | Check system pressure, check water pressure sensor. |
| 119 | Water pressure switch has cut out 6 | Check water pressure. |
| 125 | Maximum boiler temperature exceeded | Check water flow rate, check pumps, check controls. |
| 128 | Loss of flame during operation | Check connections to flame probe. Investigate flame probe condition. Check combustion when boiler is firing. |
| 130 | Flue gas temperature limit exceeded | Check the cause of high flue gas temperature. Check sensor. |
| 132 | Safety shutdown | Check gas pressure. Check flue & condensate trap for blockages. Check safety switches. |
| 133 | Safety time for establishment of flame exceeded | Check connections to flame probe. Investigate flame probe condition. Check combustion when boiler is firing. |
| 146 | Sensor/actuator configuration error | Check parameter setting. |
| 151 | BMU fault internal | Check connections to clip in, replace module, check LMS. |
| 152 | Parameterization error | Check parameters. |
| 153 | Unit manually locked | Reset button pressed to long (code appears if reset button is pressed when there are no faults). |
| 160 | Fan speed threshold not reached | Check fan connection, replace fan |
| 162 | Air pressure switch does not close | Check air pressure switch cable and connections |
| 164 | Flow/pressure switch heating circuit error | Check flow pressure switch and cable and connections. |
| 166 | Air pressure switch error does not open | Check air pressure switch and cable and connections. |
| 170 | Water pressure primary | Check flow pressure switch cable and connections. |
| 176 | Water pressure 2 too high | Check system pressure. |
| 177 | Water pressure 2 too low | Check system pressure. |
| 178 | Limit thermostat HC1 | Allow the boiler to cool and reset thermostat. Investigate cause of overheating. |
| 179 | Limit thermostat HC2 | Allow the boiler to cool and reset thermostat. Investigate cause of overheating. |
| 183 | Unit in parameterization mode | Escape back to main screen. |
| 193 | Start prevention | Check external controls. |
| 217 | Sensor error | Check connection, check sensor, check cable |
| 320 | DHW charging temp sensor fault | Check connection, check sensor, check cable |
| 321 | DHW outlet sensor fault | Check connection, check sensor, check cable |
| 322 | Water pressure 3 too high | Check system pressure. |
| 323 | Water pressure 3 too low | Check system pressure. |
| 324 | Same sensor Input BX | Check parameters. |
| 325 | Same sensor Input BX/extension module | Check parameters. |
| 326 | Same sensor Input BX/mixing valve group | Check parameters. |
| 327 | Same function mixing valve group | Check parameters. |
| 328 | Same function mixing valve group | Check parameters. |
| 329 | Same funct ext module/mixing valve group | Check parameters. |
| 330 | Sensor input BX1 no function | Sensor not Parameterised. |
| 331 | Sensor input BX2 no function | Sensor not Parameterised. |
| 332 | Sensor input BX3 no function | Sensor not Parameterised. |
| 333 | Sensor input BX4 no function | Sensor not Parameterised. |
| 335 | Sensor input BX21 no function | Sensor not Parameterised. |
| 336 | Sensor input BX22 no function | Sensor not Parameterised. |
| 337 | Sensor input B1 no function | Sensor not Parameterised. |
| 338 | Sensor input B12 no function | Sensor not Parameterised. |
| 353 | Cascade flow sensor B10 missing | Sensor not Parameterised. |
| 372 | Limit thermostat HC3 | Allow the boiler to cool and reset thermostat |
| 385 | Mains undervoltage | Check incoming voltage. |
| 386 | Fan speed tolerance | Check fan connection |
| 387 | Air pressure tolerance | Check air pressure switch |
| 388 | DHW sensor no function | Sensor not parameterised . |
| 429 | Dyn water pressure too high | Check water pressure. |
| 430 | Dyn water pressure too low | Check water pressure. |
| 432 | Function ground missing | Check earth connection. |
| 433 | Heat exchanger temperature | Allow the boiler to cool and reset thermostat |
Source: Hamworthy Heating — fault code tool. Codes and meanings can differ between versions and control software — always check the manual for your exact appliance.
Figures are typical for UK natural gas. The current edition of the relevant IGEM standard and the manufacturer's instructions always take precedence on site.
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