Sime boiler problem and effective solutions


When a Sime boiler has a problem, it will display an error code on the control panel display. Generally speaking, this error code system is quite precise as the solutions provided in the manual for each error code are easy to put into practice. In this article, we will take a look at the error codes in Sime boilers, as well as the causes of these codes and some effective solutions for each one. We will also include a table summarizing or organizing everything clearly.

How to understand Sime boiler problems

Like most modern boilers, Sime boilers are designed with an electronic card that precisely manages their operations. They also come with a display and error code system that gives suggestions for each operating anomaly or breakdown, including some possible solutions.

As is the case with other boilers, Sime boilers have problems that can be corrected automatically, while others need human intervention, namely if the user must restart or reset the boiler, or if technical assistance is needed.

When a Sime boiler has a problem, the error code structure is F + Digit. For instance, the display will show: F01 when the safety thermostat detects temperature excess, F02 indicates that the sanitary probe has a short circuit, while F04 indicates no flame or a flame detection failure, and so on.


Sime Format boiler problems: summary table

Below we will show problems that can occur in the low NOx Sime Format boiler. However, these problems can also occur in other models from the brand. Click or tap on this link if you need to download the manual for Bass NOx Sime Format.

CodeError Code CauseSolution
F01Blockage due to excess temperature. The safety thermostat (TS) has intervened. The boiler is not starting and the burner is blocked.Press the reset key (RESET) on the control panel to restart the unit.
F02Problems with the sanitary probe (SS) if there is one. The sensitive portion of the sanitary probe is open or has a short circuit.Call in a technician to replace the sanitary probe.
F03There is a problem with the heating probe (HP). The sensitive part of the heating probe is open or has a short circuit.Call in a technician to replace the heating probe.
F04No flame detected at the end of the starting sequence due to no flame or because the card cannot detect one. Also, flame detection is giving error code F04.Press the RESET key on the control panel and restart the unit. It can only be restarted up to 5 consecutive times. After this, you’ll need to call in a technician to address the fault.
F05Indicates an air pressure anomaly that is below the transducer threshold. If the correct pressure value is not detected after 10 seconds of fan activation, F05 will appear until the pressure normalizes.The error should resolve automatically, after which the boiler will restart and continue to operate as normal. Otherwise, call in a technician.
F06Indicates that there are errors or faults with the external probe (if there is one). If the external probe is open, incorrectly installed or has a short circuit, the boiler will not work.Call in a qualified technician to repair, install or replace the external probe.
F07Indicates that the air transducer is malfunctioning (open or shorted). The boiler will not work.Call in a qualified technician to repair or replace the air transducer.
F08Indicates an abnormality in the air pressure with the fan not working. This happens when the boiler is operating and detects air but the fan isn’t receiving power. The system stops working.Call in a qualified technician to repair or replace the air detection device or fan.
F09Indicates a problem in the sealed/open configuration, possibly a problem with the X15 card connector wiring. The boiler has stopped working.Call in a qualified technician to configure the open/sealed system properly, or readjust the wiring.
F10Indicates a problem caused by low water pressure. The pressure switch is detecting pressure less than 0.5 bar and the boiler has stopped working.The unit needs to be filled with water, and the valve needs to be opened until the pressure is restored to between 1 and 1.2 bar (we will discuss this procedure in detail later).
F11Indicates that there is a problem due to lack of water circulation. Lack of water circulation is detected whenever the probe detects a temperature reading greater than 5 deg C per second. In this case, the boiler will stop working and won’t restart until the heating probe detects a temperature of 45 deg or lower.The water circulation pump needs to be unblocked or replaced. This job should be carried out by a qualified technician.

How to restart or reset a Sime boiler with burner problems

When the burner misfires, the red LED light signaling a blockage will light up automatically. To reset or restart the boiler again, turn the position selector knob and then release it quickly, placing it back in winter or summer mode.

If you need to check a blockage in the boiler again, you may need to call in a qualified technician. Either way, the boiler cannot be restarted or reset more than 5 consecutive times as this is a sign that there is a major problem that should be sorted out before it can function normally again.

Low pressure problems in Sime boilers: how to reset

If a Sime boiler is experiencing problems and is displaying error code F10, this means that (as we have already seen in the table) it has low pressure. The cause of this is normally due to a lack of water. This is often the case with gas boilers and Sime boilers. A basic solution is to fill the unit with water. To do this, follow these easy steps:

  1. Locate the boiler’s telescopic loading knob (you can find out where this is in the manual).
  2. Lower the telescopic mechanism on the knob to activate it and turn it anticlockwise. Normal Sime boiler pressure when there is no problem is always between 1 and 1.2 bar, which is often indicated on a blue scale. Allow the water to flow into the unit until the pressure reaches the correct level.
  3. Once the pressure has normalized, remember to close the filling or charging cock, otherwise excess water will enter and cause an abnormal pressure increase.
  4. Regularly check the boiler’s pressure and ensure that it is consistently normal.
  5. If you notice that the pressure (when the unit is cold) is less than 1 bar, fill the unit with water following the steps just indicated.
  6. If the unit needs to be filled with water too often, this is a sign of a leak, which may be in the safety valve, somewhere else in the unit, or elsewhere in the boiler.

Sime Format boiler problems: The chimney sweep function

When there are problems with the smoke outlet pipe, Sime Format boilers have the so-called “chimney sweep function” to address this problem. This checks and cleans the smoke outlet pipe.

Get Sime boiler spare parts for your business from Suner

The Suner online store offers you a wide and varied range of Sime boiler spare parts for your business. We also offer you a wide and assorted range of spare parts for wall-mounted boilers and burners from many different leading boilers and domestic hot water generator brands in the market.


Make Suner your chosen supplier for spare parts for your business and we will ensure an uninterrupted supply of genuine parts that have been made according to the highest standards of quality and durability. We offer fast and secure shipping and great after-sales service that is suitable for any business model.

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