How do you fix Goodman E6?

Book a service call before the furnace fails rather than after. This is the rare code that gives warning, and the repair is usually inexpensive. Cleaning a flame sensor is technician work. It sits in the burner flame, in the circuit that decides whether gas keeps flowing, and refitting it wrongly recreates the failure it was meant to fix. Full steps and safety notes are on this page.

Goodman furnace E6: Flame signal is too weak

E6 means the furnace is lighting and running, but the control can barely detect the flame. It is a warning ahead of a failure — the furnace still heats, and before long it will not.

Applies to: Goodman GMVC96, GMVM97, GCVC96, GCVM97 and Amana AMVC96, AMVM97 series gas furnaces with a two-character alphanumeric display.

What it means

Flame detection works by rectification: the control applies a small voltage to the flame sensor and reads the tiny current that flows through the flame itself, measured in microamps. E6 means that current is above zero but low enough for the control to flag it. That makes this an unusual and genuinely useful code — a predictive fault rather than a failure. The furnace is still working while it is displayed. Left alone, the signal keeps falling until it drops below the threshold, at which point the furnace can no longer prove flame, shuts the gas off, and eventually locks out with E0 instead.

Most common causes

The flame sensor is coated with oxide or carbon, insulating it from the flame. This is the most common cause by a wide margin.
The sensor is bent or has shifted so it sits only partly in the flame.
Poor furnace grounding, since rectification needs a solid ground path.
A weak or lazy burner flame caused by low gas pressure.
Restricted combustion air, producing a flame that carries current poorly.
A cracked ceramic insulator on the sensor, leaking signal to the cabinet.
Corroded or loose wiring between the sensor and the board.

How to diagnose it

Note that the furnace is probably still heating. This code often appears while everything seems fine, which is exactly when acting on it is cheapest.
Check whether the furnace has started short-cycling or occasionally failing to stay lit. That is the signal falling further.
Check when it was last serviced. A sensor uncleaned for several seasons is the usual explanation.
Mention any other intermittent electrical oddities to the technician, since poor grounding causes this and several other faults together.

How to fix it

Book a service call before the furnace fails rather than after. This is the rare code that gives warning, and the repair is usually inexpensive.
Cleaning a flame sensor is technician work. It sits in the burner flame, in the circuit that decides whether gas keeps flowing, and refitting it wrongly recreates the failure it was meant to fix.
Have grounding checked at the same visit if the sensor was cleaned recently and the code has come back.
Low gas pressure needs correcting at the valve or the supply, which is also licensed work.

Notes

A flame sensor is a plain steel rod with a ceramic insulator and no moving parts, and cleaning it takes minutes. Worth knowing, because the alternative outcome is the same repair carried out on the coldest night of the year at emergency rates.

All codes for this manufacturer

Goodman and Amana furnace fault codes — every code, with what differs between models.

Models this code appears on

From the manufacturer's per-model database. If your model is not listed, this code may not exist on your board, or it may mean something different — check the model page.

The same warning on other control families

The weak-flame warning translates across every display generation: Trane E08 calls it flame current low but usable, Lennox E240 logs low flame current in run mode, and Goodman's own single-LED ancestors flash it as seven flashes. All the versions catalogued on the flame sensor hub share the trait that makes this family unusual: the furnace is still heating while the code shows. Warnings with working heat behind them are rare in this hobby, and worth taking while they last.

What the fix costs

This is the code that usually ends in the cheapest real repair a furnace offers: flame sensor cleaning at $80–200, the job the repair cost guide describes as ten minutes and the classic easy fix. E6's economics are entirely about when, not what. Attended while the furnace still runs, it is a short scheduled visit at standard rates; ignored until the flame signal sinks below the control's threshold, the same oxide film on the same sensor rod presents as a no-heat lockout, at which point the same ten minutes may arrive wrapped in a $100–200 after-hours premium and a cold evening. Few codes make the case for promptness this cleanly.

DIY or call a pro?

Forums will tell you sensor cleaning is a homeowner job; this site's line is that the flame sensing circuit — the mechanism by which a gas furnace proves its own burn — belongs to professionals, and E6 does not change that. What the code hands the homeowner instead is control of the schedule. Book the short visit this week, name the code when you do, and mention how long the display has been showing it, because a signal that has drifted down over a month reads differently to a technician than one that fell off a cliff yesterday. If lockout beats the appointment, the E6 history is the first thing to report.

What this looks like

From the outside, this usually shows up as the burner lights and then drops out a few seconds later — that walkthrough covers what to check in order, and when it stops being a homeowner job.

Sources

Goodman Manufacturing — Diagnostic Code Identification System (model-specific fault code lookup)

This site is a reference, not a substitute for a licensed HVAC technician. Gas appliances can leak carbon monoxide and cause fire. Anything involving gas lines, the heat exchanger, or the flame sensing circuit should be handled by a licensed professional. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.