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 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 37 The AL 37 code appears when the boiler's control board detects that the incoming mains electrical supply voltage has… 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 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 96 AL 96 is a blocking (permanent) lockout fault indicating that the boiler's main electronic control board (PCB) has… Read more →