High
Return Thmr Fault on Ideal Evomax

Your boiler is temporarily unable to accurately measure the temperature of the water returning to it, so it has safely shut down to prevent overheating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Return thermistor fault

Shared across the Evomax range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

Flow Thmr FaultView →L F Thmr FaultView →L R Thmr FaultView →

All 34 fault codes on the Evomax

Seeing a different code? Every code this model can display, in one place.

16767778798081828384858687888990BCC FaultCylinder Thermistor FaultError 20Ext’ Interlock OffFalse Flame LockoutFan FaultFlame LossFlow Thermistor FaultFlow/Return ReversedIgnition LockoutIgnition Lockout [16]Low Mains VoltageLow Water PressureOutside Sensor FaultOverheat LockoutPCB FaultToo Many Resets

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