Flame sensor microamp test and cleaning (measuring flame signal)

Measure the actual flame current in series with a µA DC meter before and after cleaning. A clean sensor with a low reading points to ground, wiring, board or burner flame problems rather than the rod itself.

Single source ~30 min moderateBrands: All

Before you start

This test is made with the furnace firing: keep hands clear of the burner box and wiring.
Do not adjust gas pressure or burners: blocked, refer to a licensed gas technician.

Diagnostic steps

Unlock all 8 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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