Furnace gas valve fault codes by manufacturer

Gas valve codes are the shortest list on this site and the one where the advice is most consistent: stop and call a technician.

Every fault listed here is a gas-safety fault. They involve the gas valve, the burner compartment, or the heat exchanger — the parts whose failure can put combustion products, including carbon monoxide, into the air the house breathes. Do not keep resetting a furnace that reports one of these in order to hold the heat on. Have it looked at by a licensed technician, and make sure there is a working carbon monoxide alarm on every level of the home, including the level the furnace is on. The conditions that mean stop now.

What the gas valve does

The gas valve is the electrically operated valve that admits gas to the burners. On most modern furnaces it is a redundant valve — two valve seats in one body, in series — so a single failed seat cannot pass gas on its own. The control energises it only after the inducer has proved draft and the igniter has completed its warm-up.

Why one part produces several different codes

Manufacturers report gas valve faults in two ways: a circuit fault, where the control did not see the valve respond as commanded, and a flame-sensed-with-valve-closed condition, which implies the valve may be passing gas when it should be shut. On some ICP equipment the diagnostic codes come from the valve itself rather than the control board, which is why two ICP documents give different meanings for the same flash count.

Every gas valve code on this site

13 codes across 8 control families. The meaning is the manufacturer's, from the document listed at the foot of each code page.

Brand	Code	What it reports
Armstrong	12 flashes	Flame sensed without the gas valve energised
Carrier	Status code 22	Abnormal flame-proving signal — flame detected with the gas valve closed
Goodman	solid red	Internal control fault, gas valve error, microprocessor or frequency check failure
Lennox	Alert code 204	Check gas valve
Lennox	Alert code 205	Gas valve relay contact closed
Lennox	Alert code 206	Gas valve second stage relay fault
Lennox	E204	Gas valve mis-wired
Trane	7 flashes	Gas valve circuit error
Trane	E2.3	First stage gas valve not energised when it should be, ten times
Trane	E7.1	First stage gas valve energised when it should be off
Trane	E11	Gas valve relay faults — five conditions in one code
York	1 red flash	Flame sensed with the gas valve off
York	10 red flashes	Gas valve energised with no call for heat

Before you work on it

Every fault on this page involves the component that controls gas flow. None of them is homeowner-serviceable. If there is any smell of gas, leave the building first and call the gas utility from outside.

What the fixes cost

One number governs this page: $300–900 installed, the repair guide's range for a gas valve, flagged there with the bluntest note on its price sheet — never a DIY part. There is no capacitor-style cheap variant and no cleaning that restores a valve; the meaningful cost question is confirmation, because valve codes overlap with wiring faults on several controls. A $75–150 diagnostic that proves the valve — rather than a shorted flame-sense circuit or a starved gas supply — is money well spent ahead of a $900 part. And if the furnace is old enough that a valve would join other recent repairs, run the repair-times-age arithmetic against the replacement cost guide before approving.

Do it yourself or call someone?

This page's advice does not bend: every code above involves the component that controls gas flow, and none of it is homeowner-serviceable. The homeowner's entire role is shutdown and reporting — furnace off at the service switch, note the code and what the furnace was doing when it appeared, and if there is any smell of gas, leave the building and call the gas utility from outside before calling anyone else. Do not power-cycle to see whether a valve code clears; a control that suspects its own gas valve should be believed until a professional proves otherwise.

Other parts

Sources

Every code meaning above comes from the manufacturer document behind its code page:

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.