Goodman five flashes: flame sensed when no flame should exist
Goodman five flashes means the control sensed flame with the gas valve closed. Understand why this is treated as urgent and why no reset belongs here.
What this means
Five flashes on a Goodman integrated control reports flame sensed when there was no call for heat and the gas valve should have been closed. The control is describing gas burning outside the sequence it commanded, which is why the response is to shut down and involve a licensed engineer rather than to reset and observe.
Equipment and model context
Goodman GMVC-series two-stage variable-speed gas furnaces documented in the installation and operating instructions
- GMVC80
- GMVC95
- GMVC96
What follows is scoped to GMVC-series equipment and the flash table Goodman prints for it. Other Goodman control generations, and related brands built on similar boards, assign this count differently, so the diagnostic label fixed inside your own furnace door is the authority rather than any chart found elsewhere.
What you may notice
- The control LED repeats five flashes while the furnace is not being called on to heat.
- The circulating blower or the inducer runs when nothing has asked for heating.
- The furnace behaves as though it is heating at times the thermostat is satisfied.
Likely causes
- A gas valve that does not close fully allows gas to reach the burner after the control has commanded it shut.
- Residual flame from a delayed shutdown can persist past the point the control expects the burner to be out.
- A flame sensing circuit fault can report a signal that no real flame is producing.
Diagnostic paths
You can see or hear burner activity with no heat call
Burner noise, a glow through the sight glass, or heat from the cabinet occurs while the thermostat is satisfied and nothing has asked for heating.
Switch the furnace off at the service switch and close the manual gas valve serving it if you know where it is and it is accessible, then call a licensed gas engineer.
The code shows but the furnace appears completely idle
Five flashes repeat on the control, yet no burner activity, heat, or smell is apparent from outside the cabinet.
Still stop using the furnace and arrange service. A sensing circuit reporting a flame that is not there needs correcting before the control can be trusted with a real one.
It appears right at the end of every heating cycle
The code shows up consistently in the moments after a normal heating cycle finishes rather than at random times.
Note that timing precisely. Flame lingering past shutdown is a different investigation from flame appearing during an idle period.
Flame proving normally answers whether a commanded flame arrived. This code answers the mirror question, whether an uncommanded flame is present, and a yes there carries different weight than a no to the first.
- Valve commanded shutNo gas should reach the burner
- Sensor still reads flameSomething is burning anyway
- Control shuts downBlower may run to remove heat
- Engineer requiredThe gas train needs testing
| What you observe | How to treat it | Why |
|---|---|---|
| Burner active with no call | Emergency, isolate and call | Uncommanded combustion |
| Gas smell of any kind | Evacuate and use the emergency line | Gas escape outranks everything |
| Code only, furnace idle | Stop using it, arrange service | The safety chain is unreliable |
| Code after every cycle | Stop using it, report the timing | Shutdown behaviour needs checking |
Why this code gets no reset advice
Almost every furnace code on this site comes with a note about what a reset does and does not achieve. This one does not, and the omission is deliberate. A reset is a way of asking the equipment to try again, and the thing being reported here is that the equipment did something nobody asked for. Trying again is not a diagnostic step when the complaint is uncommanded combustion.
The other reason is that the two candidate causes point at the gas train itself. A valve that does not seat and a burner still alight after shutdown are both conditions where the next cycle is the risk, not the diagnosis. That takes the decision out of the homeowner's hands in a way most codes do not.
What an owner can still usefully do
Three things. Establish whether there is any smell of gas, because that changes the response from a service call into an evacuation and an emergency number. Isolate the furnace at its service switch so the control stops cycling. And record whether burner activity was actually observed or whether the code appeared with the furnace apparently idle, because those are different faults sharing one number.
Beyond that the boundary is firm. Manual gas valves, burner inspection, and gas train testing belong to a licensed engineer, and nothing about this code is an exception to that. The flame sensing explainer covers how the proving circuit works, and the safety guidance on furnace codes is worth reading before any heating fault is investigated at home.
What to give the technician
Tell the engineer the Goodman model and serial number, the five-flash count, whether burner activity was observed, at what point in the cycle the code appears, and whether any gas smell was noticed.
Safe homeowner checks
- Check for any smell of gas indoors, and if one is present leave the property and use the emergency number your gas supplier publishes before doing anything else.
- Switch the furnace off at its dedicated service switch so the control stops attempting cycles.
- Note whether you actually saw or heard burner activity, or whether only the code was present, and record the time.
When to call a technician
- A gas valve that does not seat, a burner alight outside its commanded sequence, and flame sensing circuit faults are licensed gas engineering work without exception.
- Do not operate, reset, or test the furnace to see whether the code returns. The condition being reported is combustion the control did not ask for.
Questions people ask about this
Is a Goodman five-flash code dangerous?
It reports flame sensed when the gas valve should be closed, which describes combustion the control did not command. That is treated as an urgent condition needing a licensed engineer rather than a fault to observe.
Could this just be a faulty flame sensor?
A sensing circuit reporting a flame that is not there is one of the possibilities. It still means the safety chain cannot be trusted with a real flame, so the furnace is taken out of use either way.
Why does the blower run when nothing called for heat?
The control runs the circulating blower to remove heat from the exchanger when it detects flame outside the commanded sequence. It is a protective response rather than a sign the thermostat is calling.
Evidence recordHow this page was checked
service manual · checked 2026-09-15
Every technical claim above was written from primary documentation held in the HVAC Bench evidence record: Goodman technical literature. Where a source limits a definition to certain models, test conditions, or product classes, that limit is repeated here rather than generalised.
- Documentation class
- service manual
- Scope of the definition
- Goodman GMVC-series two-stage variable-speed gas furnaces documented in the installation and operating instructions
- Last checked
- 2026-09-15