Unit displays Code 35 and will not operate

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

Incorrect thermistor wiring, Multiple thermistors on wrong connectors, Damaged harness, Faulty control board

Safety first: Turn OFF power and gas before opening the unit.

Steps to check:

Inspect thermistor connectors: Verify each thermistor (inlet, outlet, heat exchanger, flue) is plugged into the correct labeled socket on the control board.
Check harness integrity: Look for pinched or cut wires in the thermistor harness bundle.
Reset and test: After correcting any miswiring, restore power and gas and reset the unit.

When to call a professional: If Code 35 remains, the harness or control board may need replacement by a technician.

Hard 4/5

Thermistor Harness

Check Price on Amazon

We may earn a commission from links on this page.