Ideal Ionisation Harness 178158

The Ideal 178158 is an ionisation harness — the wiring lead that carries the flame-sensing signal from the ionisation electrode back to the control board. It is manufactured by Ideal and supplied as a replacement for the original lead on Ideal Commercial appliances.

The harness sits in the combustion circuit. The control board passes a small rectification current through the electrode and the flame; the harness is the conductor that returns that signal, so the PCB can confirm a burner flame is present and hold the appliance in run mode.

• The burner lights, then locks out a short time later with the board reporting no flame.
• Repeated flame-failure lockouts that clear on reset and then return.
• Unstable or intermittent flame signal readings taken during a service check.
• Visible damage to the lead — cracked or brittle insulation, chafing, or heat marking near the electrode end.
• Corroded, loose or discoloured pins in the harness plug, or a plug that no longer clips home firmly.

• Confirm the appliance model and serial number against the compatibility list, as the Imax XEL range covers several output sizes.
• Compare the connector type and lead length on the existing harness with the replacement before fitting.
• Inspect the ionisation electrode and its sealing washer at the same time; a worn electrode can produce the same symptoms as a faulty harness.