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Sime Boiler Fault Codes and Errors
Over the years, Sime boilers have made their way into several UK households where they are relied upon for domestic hot water supply and central heating. And like any other boiler brand, these Sime boilers are also designed to display error codes when they have an internal issue.
Therefore, if you come home to your boiler displaying fault codes, you shouldn’t panic. This is because the boiler is trying to help you pinpoint the internal issue it has. As such, all you need to do is understand the meaning of the displayed error code and, from there, decide the next course of action.
That said, here are the common Sime boiler fault codes, possible causes, and even their solutions.
| Fault
Code |
Description/ Possible causes | Fixes |
| AL 02 | The water pressure in the boiler system is low | Repressurise the boiler. If the error doesn’t clear, then there might be a leak in the system, and you need to contact a heating engineer. |
| AL 03 | Excessive water pressure in the boiler I system | Drain the excess water in the system by opening the drain valve. When the water pressure reaches around 1.2 bars, close the drain valve. Ensure you don’t excessively drain the system to prevent an AL 02 error. |
| AL 04 | The domestic hot water sensor is faulty. Probably due to short-circuiting or it being damaged. | Check the sensor connections for any loose wirings. If there are none, then you may have to replace the sensor. |
| AL 05 | The delivery sensor is faulty. Probably due to some faulty connections or it is damaged. | Check the sensor connections for any loose wirings. If the sensor is damaged, it may need replacing. |
| AL 06 | Flame detection error, possibly due to a faulty flame detection electrode, faulty gas valve, or a gas supply issue. | Check your gas supply to ensure that there is a steady supply of gas under sufficient pressure. Next, check whether the gas valve is functioning well. Once confirmed, reset the boiler. |
| AL 07 | There is an issue that prompted safety thermostat intervention. | Start by checking the sensor or thermostat connections. If the wiring is messy or the sensor or thermostat is damaged, you may need to call in a heating engineer to fix or replace them. Next, bleed your boiler system to remove any trapped air and ensure that the pump impeller is not blocked. |
| AL 08 | There is an issue with the flame detection circuit, due to a faulty electrode, gas supply issues, or a faulty gas valve. | Check your gas supply to ensure that there is a steady supply of gas under sufficient pressure. Next, check whether the gas valve is functioning well. Once confirmed, reset the boiler, and if the error doesn’t clear, call a heating engineer. |
| AL 09 | There is no water circulating in the boiler system due to a faulty pump or an electrical issue. | Ensure that the pump impeller is working correctly. Also, check the electrical connections to the pump to ensure there are no loose ones. Next, reset the boiler, and if the error code doesn’t clear, your pump may need replacing. |
| AL 10 | The boiler’s auxiliary sensor is faulty due to a misconfiguration or an electrical connection issue. | Ensure the boiler’s hydraulics are correctly configured and that the auxiliary sensor has no loose electrical connections. As this is a demanding task, you’ll be better off leaving it to a certified heating engineer. |
| AL 11 | The pump’s gas valve modulator is disconnected. | As this is usually an electrical problem, you should call a certified heating engineer to fix it. |
| AL 12 | The pump’s open or sealed chamber is not correctly configured. This is usually due to the wrong combustion configuration. | Set the parameter tS 0.4 to 0. |
| AL 13 | The exhaust sensor intervention feature has been activated, usually caused by the smoke probe having faulty electrical connections or being damaged. | Replace the smoke probe, and if it does not work, contact a heating engineer. |
| AL 14 | The exhaust sensor intervention feature has been activated. This is usually caused by the smoke probe having faulty electrical connections or being damaged. | Replace the smoke probe and if it does not work, contact a heating engineer. |
| AL 15 | The fan check cable is disconnected | Contact a heating engineer |
| AL 18 | This indicates the presence of a condensate level fault | Check your condensate pipe and siphon for any clogging, and if present, clear it. |
| AL 28 | The number of maximum resets has been reached. This means there have been six consecutive resets. | Leave the boiler for some time, then attempt to reset it again. If it doesn’t work, contact the Technical Assistance Centre. |
| AL 30 | The return sensor is faulty. | Replace the return probe and reset the boiler. If it doesn’t work, contact a heating engineer or the Technical Assistance Centre. |
| AL 37 | Low network voltage, usually less than 170V | Contact a heating engineer or the network provider (ENEL) |
| AL 40 | The supply frequency is incorrect | Contact the network provider (ENEL) |
| AL 41 | A flame loss has occurred more than six consecutive times. This is usually attributed to a faulty flame detection electrode, a closed gas valve, low gas pressure, or even lack of gas. | Check the gas valve to ensure it is open. Next, check that there is a steady supply of gas at the correct mains pressure. If all these are good, the issue lies with the flame detection electrode, and you need to call a heating engineer. |
| AL 42 | Implies presence of a button fault | Check that all your boiler’s buttons are working. |
| AL 43 | There has been an open thermostat communication fault, usually due to a faulty remote control. | Ensure the remote control has no wiring issues |
| AL 62 | A request for the self-calibrating procedure to be initiated | Initiate the self-calibrating procedure |
| AL 72 | The delivery sensor has been incorrectly placed | Ensure the delivery sensor is attached to the delivery pipe |
| AL 77 | Indicates the presence of an EV2 SGV current maximum or minimum limit error | Contact the Technical Assistance Centre |
| AL 78 | Indicates presence of an EV2 SGV current upper limit error | Contact the Technical Assistance Centre |
| AL 79 | Indicates presence of an EV2 SGV current lower limit error | Contact the Technical Assistance Centre |
| AL 80 | There is a fault on the valve control logic line, or the valve cable is damaged. | Check the valve cable for any visible damages and if there are none, contact the Technical Control Centre. |
| AL 81 | There has been a block due to combustion. It usually happens during boiler start-up. | Check your boiler’s chimney for any blockages and clear them. Next, bleed any air that is trapped in your boiler system. |
| AL 82 | There has been a block due to numerous combustion failures | Check the boiler’s electrodes to see if they are faulty. Also, check the boiler outlets for any blockages. |
| AL 83 | Indicates there is irregular combustion in the boiler, usually a temporary problem attributed to a blocked chimney | Clear the chimney of any blockages |
| AL 84 | There is a low gas flow rate due to low pressure on the gas mains supply. | Check the gas line for low pressure |
| AL 88 | There has been an internal error resulting in the activation of the board component protection feature. | Contact the Technical Assistance Centre |
| AL 89 | There is unstable combustion in the boiler, prompting a feedback signal error. | Contact the boiler Technical Assistance Centre |
| AL 90 | This means the combustion set cannot be reached | Contact the boiler Technical Assistance Centre |
| AL 92 | Maximum air correction error | Contact the Technical Assistance Centre |
| AL 93 | The combustion set cannot be reached | Contact the Technical Assistance Centre |
| AL 95 | Indicates a flame signal micro interruptions error | Contact the Technical Assistance Centre |
| AL 96 | The smoke outlet is clogged, resulting in a blockage | Inspect the boiler’s chimney and clear any blockages |
| AL 98 | An SW error occurred during the board start-up | Contact the Technical Assistance Centre |
| AL 99 | There is a general PCB error | Contact the boiler’s Technical Assistance Centre |
| – | Frequent relief valve intervention due to boiler pressure issues | Check the boiler’s expansion vessel and circuit pressure for any anomalies |
| – | Implies there is a limited production of hot water from the boiler | Ensure the domestic hot water circuit valve is working correctly. Also, check the diverter valve and clean the plate heat exchanger. |