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Sime Fault Codes
Select a fault code to see its meaning, common causes and how to fix it.
- AL 01 The AL 01 fault code on a Sime boiler signals that the water pressure within the central heating circuit has dropped… Read more →
- AL 02 The AL 02 fault code on a Sime boiler indicates that the water pressure in the central heating circuit has dropped… Read more →
- AL 03 AL 03 indicates that the water pressure inside your sealed heating system has climbed too high. When the boiler detects… Read more →
- AL 04 The AL 04 code appears on Sime boilers when the control board loses confidence in the readings from the domestic hot… Read more →
- AL 05 The AL 05 code on a Sime boiler indicates a problem with the delivery (flow) temperature sensor — the NTC thermistor… Read more →
- AL 06 AL 06 on a Sime boiler signals that the boiler has attempted to ignite but failed to detect a flame — a condition known… Read more →
- AL 07 The AL 07 code appears on Sime boilers when the built-in safety thermostat (TS) has triggered a protective shutdown.… Read more →
- AL 08 AL 08 indicates that your Sime boiler has detected a problem within the flame detection circuit — the electronic system… Read more →
- AL 09 The AL 09 fault code (displayed as ALL 09 on some Sime models) means the boiler's flow switch has detected insufficient… Read more →
- AL 10 When your Sime boiler displays AL 10, it has detected a problem with the central heating flow NTC (Negative Temperature… Read more →
- AL 11 The AL 11 code appears on Sime boilers — including the Brava One HE 25 and Brava Slim HE — when the PCB has detected a… Read more →
- AL 12 AL 12 on a Sime boiler means the control board's combustion-chamber configuration does not match what the boiler… Read more →
- AL 13 The AL 13 code on a Sime boiler indicates that the control board has detected a problem with the flue gas (exhaust)… Read more →
- AL 14 When your Sime boiler displays AL 14, it has detected a problem with the flue or exhaust gas temperature sensor… Read more →
- AL 15 AL 15 appears on Sime boilers — including the Brava Slim HE and Brava One HE series — when the control board detects a… Read more →
- AL 18 AL 18 appears on Sime boilers when the PCB has detected a problem with the central heating flow NTC (temperature)… Read more →
- AL 28 The AL 28 code is Sime's way of signalling a serious internal or electronic fault that goes beyond routine diagnostics.… Read more →
- AL 30 AL 30 on a Sime boiler indicates a fault with the return temperature sensor — the probe measuring the temperature of… Read more →
- AL 37 The AL 37 code appears when the boiler's control board detects that the incoming mains electrical supply voltage has… Read more →
- AL 40 AL 40 on a Sime boiler means the control board has detected that the frequency of the incoming mains electricity is… Read more →
- AL 41 The AL 41 code appears on Sime boilers when the burner flame has been lost six times in a row during the ignition… Read more →
- AL 42 AL 42 on a Sime boiler is a button fault: the control board has detected that one of the panel buttons is misbehaving —… Read more →
- AL 43 The AL 43 fault code on a Sime boiler indicates a problem with the central heating return sensor, known as the SR… Read more →
- AL 44 AL 44 on a Sime boiler is a gas valve timeout fault without flame: the control board commanded the gas valve during an… Read more →
- AL 56 AL 56 on a Sime boiler is a lock caused by the temperature difference between flow and return exceeding its maximum… Read more →
- AL 57 AL 57 on a Sime boiler is a lock raised by the flow temperature (FT) check — the board's supervision of how the flow… Read more →
- AL 62 AL 62 on a Sime boiler means the appliance is demanding its automatic self-calibrating procedure be carried out. Sime's… Read more →
- AL 72 AL 72 on a Sime boiler flags incorrect positioning of the delivery (flow) sensor: the board's plausibility checks have… Read more →
- AL 74 AL 74 on a Sime boiler reports a fault with the second delivery sensor. Sime's combustion-control models monitor flow… Read more →
- AL 77 AL 77 belongs to the family of SGV gas-valve supervision faults on Sime's combustion-control boilers. The board… Read more →
- AL 78 AL 78 is one of Sime's SGV gas-valve supervision codes: the current measured through the valve's EV2 operator has… Read more →
- AL 79 AL 79 completes Sime's trio of SGV valve-current codes: the current measured through the gas valve's EV2 operator has… Read more →
- AL 80 AL 80 on a Sime boiler reports a fault on the gas valve's control logic line — including the case Sime calls out… Read more →
- AL 81 AL 81 on a Sime boiler is a block caused by combustion problems during start-up: the combustion-control system watched… Read more →
- AL 82 AL 82 on a Sime boiler is the block raised after numerous combustion-control failures — the boiler has tolerated… Read more →
- AL 83 AL 83 on a Sime boiler flags irregular combustion as a temporary error: the combustion-control system saw a burn… Read more →
- AL 84 AL 84 on a Sime boiler means the combustion controller has had to reduce the boiler's flow rate because it suspects low… Read more →
- AL 88 AL 88 on a Sime boiler is an internal error raised by the control board's own protection — a component-level fault… Read more →
- AL 89 AL 89 on a Sime boiler means the combustion feedback signal is unstable: the flame-sensing signal the combustion… Read more →
- AL 90 AL 90 on a Sime boiler means the combustion controller cannot reach its combustion set point: the closed-loop system… Read more →
- AL 92 AL 92 on a Sime boiler means the combustion controller has reached the maximum air correction available (at the minimum… Read more →
- AL 93 AL 93 on a Sime boiler is a combustion set cannot be reached error — the sibling of AL 90, distinguished internally by… Read more →
- AL 96 AL 96 is a blocking (permanent) lockout fault indicating that the boiler's main electronic control board (PCB) has… Read more →