Furnace Repair Services › Furnace Flame Sensor Cleaning
Furnace Flame Sensor Cleaning in Portland, ME
The flame sensor is a small metal rod that detects whether the burner actually ignited after the gas valve opens. If it can't sense the flame — usually because a layer of oxidation has built up on the rod — the furnace shuts the gas off as a safety measure and tries again. Most homeowners notice this as a furnace that lights briefly then goes out, cycling two or three times before locking out. Cleaning the sensor takes minutes and often solves the problem without any parts at all.
Portland Furnace Repair Pros provides furnace flame sensor cleaning for homeowners across Portland, ME. Call for a free inspection and a written quote before any work begins.
When to Call
When You Need Furnace Flame Sensor Cleaning
- Your furnace lights for a few seconds, shuts off, and repeats this two or three times before locking out
- The furnace ran fine all fall but started acting up in January after sitting during a warm stretch
- You can see the burner ignite but the furnace cuts out within five seconds every time
- Your furnace fault code shows flame failure even though the igniter clearly works
How It Works
Our Process for Furnace Flame Sensor Cleaning
- 1
Confirm the Fault Pattern
We watch the furnace attempt a full start cycle to verify the flame sensor lockout pattern before opening the cabinet.
- 2
Remove and Inspect the Sensor
We pull the sensor rod and check for oxidation buildup, surface pitting, or cracks in the porcelain insulator.
- 3
Clean the Rod
We lightly abrade the metal rod to remove oxide buildup, then reinstall it with the correct torque — a loose sensor causes recurring issues.
- 4
Measure Microamp Signal
We confirm the sensor is producing adequate microamp output with the burner running. Below spec means replacement is the right call.
Portland Context
Why this matters in Portland
Flame sensor fouling tends to show up at the start of heating season in Portland, after furnaces sit idle through summer. We clean a lot of them in October and November as part of tune-up calls that turn into no-heat calls.
Straight Talk
About pricing & scope
Cleaning is usually sufficient, but sensors that are pitted or cracked won't hold a clean reading and need replacement. We check the microamp reading after cleaning so we're not sending you into winter with a sensor that's about to fail anyway.
What This Fixes
Problems We See in Portland
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