Boiler displays E16, may be related to flue gas temperature sensor on some Sime condensing models

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Failed flue gas NTC, Damaged sensor wiring, Sensor dislodged from flue, PCB sensor input fault

Safety first: Isolate power and gas. Flue components must be handled by qualified personnel.

Visual inspection (engineer task): Locate the flue gas sensor on the flue hood or outlet. Ensure it is securely mounted and the cable is not heat-damaged.
Measure resistance: Compare the sensor resistance to Sime specifications. Replace if out of range.
Check PCB connection: Confirm the sensor harness is properly connected to the main PCB.
Reset and test: After replacement, reset the boiler and verify stable operation.

Hard 4/5

Flue Gas NTC Sensor

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