Goodman Furnace E2 Error — Flame Sense Fault
The E2 error code on Goodman furnaces with digital displays (common on newer GMSS96, GCSS96, and AVPTC series units) means the flame sensor is not detecting a flame during the trial for ignition period. The control board lights the igniter and opens the gas valve, but the flame signal never registers — so it shuts down and stores E2.
Note: Older Goodman furnaces with LED blink codes use flash sequences instead of E-codes. The E2 code appears on models with a digital segment display on the IFC board.
Why E2 Happens
| Cause | Frequency |
|---|---|
| Dirty/oxidized flame sensor rod | Very common |
| Weak igniter (not hot enough to light gas) | Common |
| Low gas pressure | Common |
| Gas valve not opening (failed coil or wiring) | Moderate |
| Flame sensor wire broken or grounded | Moderate |
| IFC board microamp circuit failed | Rare |
How the Flame Sensor Works
The flame sensor is a metal rod that extends into the burner flame. When flame is present, it passes a small AC voltage (from the IFC) through the flame to ground — creating a DC microamp signal the board reads as “flame proven.” The board expects 1–5 microamps minimum. A coated or oxidized rod can’t pass this current even when the flame is burning.
Fix Step 1 — Clean the Flame Sensor
This fixes E2 in about 60% of cases.
- Turn off power to the furnace at the disconnect.
- Locate the flame sensor — a single metal rod (usually with a white ceramic insulator) mounted in the burner area, with one yellow or orange wire attached.
- Remove the mounting screw and slide the rod out.
- Use fine steel wool or 400-grit emery cloth to lightly polish the metal rod. Remove any white/grey oxide coating until you see bare shiny metal.
- Do NOT touch the cleaned rod with bare fingers (oils will re-coat it).
- Reinstall and test.
Fix Step 2 — Test Microamp Reading
If cleaning doesn’t fix it, measure the flame sensor signal directly:
- Set your multimeter to DC microamps (µA).
- Break the wire going to the flame sensor and connect the meter in series.
- Start the furnace. When the flame lights, read the meter.
- Normal reading: 2–6 µA DC on most Goodman boards.
- Under 1 µA = replace the sensor. Consistently 0 with flame burning = suspect IFC board.
Fix Step 3 — Check Gas Pressure
Low gas pressure means a weak flame that can be hard to sense. A tech with a manometer should verify incoming pressure (7” WC for natural gas) and manifold pressure (3.5” WC standard, 10” WC for LP).
Fix Step 4 — Check Igniter
The silicon carbide or silicon nitride igniter must reach 1800°F+ to reliably ignite gas. A cracked or weak igniter may produce enough glow to start, then gas doesn’t light cleanly, then E2 trips. Visually inspect the igniter — cracks or dark spots mean replace it.
Parts You May Need
| Part | Cost |
|---|---|
| Flame sensor (universal) | Amazon | $10–20 |
| OEM Goodman flame sensor | Amazon | $25–45 |
| Hot surface igniter | Amazon | $20–50 |
| Gas valve | Amazon | $80–200 |
| IFC board | Amazon | $100–300 |
E2 vs. E1 vs. EE2
- E1 = Pressure switch fault (no draft sensing)
- E2 = Flame sense fault (no flame signal)
- EE2 = Rollout switch open (safety lockout)
Don’t confuse E2 (flame sense) with the older flash-code equivalent — 6 flashes = open limit, 7 flashes = flame sense issue on LED models.