ICP Error Code 5: Abnormal flame-proving signal (Furnace)

Updated October 13, 2026 · by Aurora Star Tech Inc.

ICP error code 5 on a furnace means: Abnormal flame-proving signal. It is also called ICP diagnostic code 5.

Critical severityFurnaceICP (F/G)9MAE Modulating Furnace

Homeowner? What ICP code 5 means for you

Stop and call Your furnace is reporting: Abnormal flame-proving signal. This code is a safety shutdown. Turn the furnace off and call a licensed technician. Do not keep resetting it. If you smell gas, leave the house and call your gas utility or 911 from outside.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does ICP error code 5 mean?

Flame is sensed while the gas valve is off. Inducer runs until the fault clears.

Applies to: ICP F9MAE / G9MAE modulating variable-speed condensing gas furnaces (060, 080, 100, 120 kBtu/h)

Common causes of ICP code 5

Gas valve stuck open or leaking through

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

ICP models that use code 5

G9MAE0601714 G9MAE0602120 G9MAE0801714 G9MAE0802120 G9MAE1002122 G9MAE1202422

Other ICP Furnace codes

Code	Meaning
3	Low pressure switch did not close or reopened
3+5	Gas valve fault (modulating valve)
4	Limit circuit fault
4+1	Blower motor fault
4+2	Inducer motor fault
4+3	Low/medium pressure switch open while medium/high switch closed
6	Ignition proving failure
6+1	Ignition lockout
7	Limit circuit lockout
8	Gas heating lockout
9	Medium/high pressure switch or PSR relay did not close or reopened
10	Line voltage polarity

All ICP Furnace error codes →

ICP code 5: homeowner questions

What does ICP code 5 mean?

Abnormal flame-proving signal. Flame is sensed while the gas valve is off. Inducer runs until the fault clears.

Is it safe to keep using my furnace with code 5?

No. Code 5 is a safety shutdown, so keep the furnace off until a licensed technician has checked it.

Can I reset ICP code 5 myself?

Do not keep resetting it. Repeated resets can hide a safety problem; a licensed technician needs to find the cause.

Who can fix ICP code 5 near me?

Aurora Star Tech Inc. repairs ICP furnaces in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean

Troubleshooting guides

Blowing cold air All brands · Furnace
No heat All brands · Furnace
Short cycling All brands · Furnace
Check inlet gas pressure ICP · Furnace
Component self-test ICP · Furnace
No heat - control does not respond to thermostat ICP · Furnace
Reading and retrieving status codes ICP · Furnace

Source: ICP (F/G)9MAE Service and Technical Support Manual 440 04 4700 00, Figure 16 Troubleshooting Chart, p.34. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.