Ideal Logic System IE fault L05
Return thermistor fault
Gas boilerWhat it means
Boiler has detected a fault with the return thermistor.
Likely causes
- Return thermistor fault as referenced in Section 4.9
- Thermistor fault requiring replacement
- Faulty or failed return thermistor requiring replacement
Where to start
- Refer to Section 4.9: Return Thermistor Fault
- Isolate and drain down the boiler
- Remove the clip from the pump housing and remove the thermistor
The full answer, free
- 2 more checks in order
- The readings and component tests from the manual
- How to put it right, step by step
- The manual page for this fault (page 49), right under the answer
Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.
From the Ideal manual for the Logic System IE. Check the model on the data plate before you order parts.
Other Ideal Logic System IE fault codes
- F02Flame loss
- F04Flow thermistor fault
- F05Return thermistor fault
- F06Outside sensor fault
- F0DLow water flow / low water pressure
- F0TRoom thermostat fault
- F0UFlow/return differential greater than 50°C
- F10Spark generator fault
- F12Pump rotor blocked
- F13Pump fault
- F15Pump fault
- F16Gas valve fault
- F17Pump fault
- F4Control/no flow thermistor fault
- F8PCB unconfigured/faulty or gas valve short circuit
- F9PCB unconfigured/faulty or gas valve short circuit
- FUDifferential greater than 50°C
- L02Ignition lockout after 5 attempts
- L04Flow thermistor fault
- L06False flame lockout / flame on before gas valve on
- L0CRepeated restart lockout
- L0DIgnition lockout: blocked flue/condensate
- L2Ignition lockout after 5 failed attempts
- L4Control/no flow thermistor fault