MECH-FILTER
Goodman · GMSS920804CN 80,000 BTU 92% AFUE Single-Stage Gas Furnace
The air filter is clogged with dust, pet hair, and debris restricting airflow through the furnace — #1 cause of furnace overheating and limit switch trips (4-FLASH code); replace disposable filters every 1-3 months during heating season; reusable filters should be washed monthly; a severely clogged filter can cause heat exchanger cracking over time
Error MECH-FILTER on the Goodman GMSS920804CN 80,000 BTU 92% AFUE Single-Stage Gas Furnace means: Dirty Air Filter — Overheating. The top-ranked community fix is “Inspect and Replace Air Filter Slot Seal and Check Blower Airflow” (medium difficulty, ~45 min, DIY cost: $5-$20). 2 community-ranked fixes available below.
Published February 2026 · 2 fixes · furnace
Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.
While many furnace repairs can be done safely at home, consider hiring a qualified technician if:
Average professional repair cost for this issue: $150-$250.
Incorrect Blower Speed / DIP Switch Configuration
System Lockout — Retry Limit Exceeded
Pressure Switch Stuck Closed
Pressure Switch Did Not Close
High Limit Switch Open
Flame Sensed Without Gas Valve Call
Flame Lost During Operation
Ignition Lockout — Failed to Ignite
The Goodman GMSS920804CN 80,000 BTU 92% AFUE Single-Stage Gas Furnace has 8 other known error codes:
Error code MECH-FILTER also appears on 2 other Goodman models:
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