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Goodman gas furnace code IdL: Idle, normal operation

Gas furnace, Canada and United States

IdL means the furnace is idle and operating normally. The control board has power and is not reporting a fault.

You can often clear this yourself. Work through the causes below in order, most likely first.

What causes it

  1. This is normal. If the house is still not heating properly, work through the owner checks for the thermostat, power, filter and grilles before calling for service.

    Check the thermostat and the power to the furnaceYou can do this

    1. Check the thermostat is working and set to HEAT above the room temperature, or to COOL below it if the problem is with cooling.
    2. If the blower runs all the time, look at the thermostat's fan switch. ON runs the blower constantly; AUTO runs it only while heating or cooling.
    3. Check that the power switch for the furnace, often a switch on or near it, is turned on.
    4. Check the electrical panel for a tripped circuit breaker or a failed fuse for the furnace. Reset the breaker or replace the fuse.
      If the breaker trips again, leave it off and call a qualified servicer.
    5. Make sure both furnace doors are in place. A switch stops the furnace from running while the blower door is off.

    Check and replace the furnace air filterYou can do this

    1. Turn off the electrical power to the furnace before you take the filter out.
      Never run the furnace without a filter in place.
    2. Find the filter. It sits outside the furnace cabinet, in a return air grille, a filter rack on the side of the furnace, or the duct next to it. If you cannot find or reach it, ask your installer.
    3. Replace a dirty disposable filter with one of the same size that meets UL900 or CAN/ULC-S111. Wash and dry a permanent filter the way its maker describes.
    4. Fit the filter so the air flows through it in the same direction as before, then turn the power back on.
    5. Check the filter at least once a month and clean or replace it when it is dirty. A dirty filter is the most common cause of a furnace not working properly.

    Clear blocked supply and return grillesYou can do this

    1. Go round the house and look at every supply register and return air grille.
    2. Move furniture, curtains, clothes, rugs or anything else that covers or blocks them.

How to read this code on your unit

The code shows on the three-character display on the furnace control board, which you can see through the sight glass on the blower compartment. IdL means the furnace is idle and normal. A blank display means the board has no power or has failed.

Models that show this code

285 models in 17 ranges
RangeModels
GM9C80 / GC9C80 / AM9C80GM9C800403AN, GM9C800403AX, GM9C800603AN, GM9C800603AX, GM9C800603BN, GM9C800603BX, GM9C800803BN, GM9C800803BX, GM9C800804BN, GM9C800804BX, GM9C800804CN, GM9C800804CX, GM9C800805CN, GM9C800805CX, GM9C800805DX, GM9C801004CN, GM9C801005CN, GM9C801005CX, GM9C801205DN
GM9C96 / GC9C96 / AM9C96GM9C960303AN, GM9C960403AN, GM9C960603AN, GM9C960603BN, GM9C960803BN, GM9C960804CN, GM9C961004CN, GM9C961005CN, GM9C961205DN, GC9C960403BN, GC9C960603BN, GC9C960803BN, GC9C961005CN
GM9S80 / GC9S80 / AM9S80 / AC9S80GM9S800403AN, GM9S800403AX, GM9S800603AN, GM9S800603AX, GM9S800603BN, GM9S800603BX, GM9S800604BN, GM9S800604BX, GM9S800803BN, GM9S800803BX, GM9S800804BN, GM9S800804BX, GM9S800804CN, GM9S800804CX, GM9S800805CN, GM9S800805CX, GM9S801005CN, GM9S801005CX, GM9S801205DN, AM9S800403AX, AM9S800603AX, AM9S800603BN, AM9S800604BX, AM9S800803BX, AM9S800804BX, AM9S800804CX, AM9S800805CX, AM9S801005CX, AM9S801205DX
GM9S92
GM9S96 / GC9S96 / AM9S96 / AC9S96GM9S960403AN, GM9S960603BN, GM9S960803BN, GM9S960804CN, GM9S960805CN, GM9S961005CN, GM9S961205DN, GC9S960403BN, GC9S960603BN, GC9S960804CN, GC9S961005CN, GC9S961205DN, AM9S960403AN, AM9S960603BN, AM9S960803BN, AM9S960804CN, AM9S960805CN, AM9S961005CN, AM9S961205DN
GR9S80 / GD9S80 / AR9S80GR9S800403AN, GR9S800403AX, GR9S800603AN, GR9S800603AX, GR9S800603BN, GR9S800603BX, GR9S800604BN, GR9S800604BX, GR9S800803BN, GR9S800803BX, GR9S800804BN, GR9S800804BX, GR9S800804CN, GR9S800804CX, GR9S800805CN, GR9S800805CX, GR9S801005CN, GR9S801005CX, GR9S801205DN, GD9S800403AN, GD9S800403AX, GD9S800603AN, GD9S800603AX, GD9S800804BN, GD9S800804BX, GD9S800805CX, GD9S801005CN, GD9S801005CX
GR9S92 / AR9S92GR9S920403AN, GR9S920603BN, GR9S920803BN, GR9S920804CN, GR9S920805CN, GR9S921004CN, GR9S921005CN, GR9S921205DN
GR9S96 / GD9S96 / AR9S96GR9S960403AN, GR9S960603BN, GR9S960803BN, GR9S960804CN, GR9S960805CN, GR9S961005CN, GR9S961205DN, GD9S960403BN, GD9S960603BN, GD9S960804CN, GD9S961005CN, GD9S961205DN, AR9S960403AN, AR9S960603BN, AR9S960803BN, AR9S960804CN, AR9S960805CN, AR9S961005CN, AR9S961205DN
GR9T80 / GD9T80GR9T800403AN, GR9T800403AX, GR9T800603AN, GR9T800603AX, GR9T800603BN, GR9T800603BX, GR9T800803BN, GR9T800803BX, GR9T800804BN, GR9T800804BX, GR9T800804CN, GR9T800804CX, GR9T800805CN, GR9T800805CX, GR9T800805DX, GR9T801004CN, GR9T801005CN, GR9T801005CX, GR9T801205DN, GD9T800403AX, GD9T800603AX, GD9T800603BX, GD9T800804BX, GD9T800805CX, GD9T801005CX
GR9T96 / GD9T96GR9T960303AN, GR9T960403AN, GR9T960603AN, GR9T960603BN, GR9T960803BN, GR9T960804CN, GR9T961004CN, GR9T961005CN, GR9T961205DN
GMVC8 / GCVC8 / AMVC8 / ACVC8GMVC80603BN, GMVC80603BX, GMVC80604BN, GMVC80604BX, GMVC80803BN, GMVC80803BX, GMVC80804CN, GMVC80804CX, GMVC80805CN, GMVC80805CX, GMVC80805DN, GMVC80805DX, GMVC81005CN, GMVC81005CX, AMVC80603BN, AMVC80603BX, AMVC80604BN, AMVC80604BX, AMVC80803BN, AMVC80803BX, AMVC80804CN, AMVC80804CX, AMVC80805CN, AMVC80805CX, AMVC80805DN, AMVC80805DX, AMVC81005CN, AMVC81005CX
GMVC80 / GCVC80 / AMVC80 / ACVC80GMVC800603BN, GMVC800603BX, GMVC800604BN, GMVC800604BX, GMVC800803BN, GMVC800804CN, GMVC800804CX, GMVC800805CN, GMVC800805CX, GMVC800805DN, GMVC800805DX, GMVC801005CN, GMVC801005CX, AMVC800603BN, AMVC800603BX, AMVC800604BN, AMVC800604BX, AMVC800803BN, AMVC800804CN, AMVC800804CX, AMVC800805CN, AMVC800805CX, AMVC800805DN, AMVC801005CN, AMVC801005CX
GMVC96 / GCVC96 / AMVC96 / ACVC96GMVC960403BN, GMVC960603BN, GMVC960803BN, GMVC960804CN, GMVC961005CN, GMVC961005DN, GMVC961205DN, GCVC960403BN, GCVC960603BN, GCVC960804CN, GCVC961005CN, GCVC961205DN, AMVC960403BN, AMVC960603BN, AMVC960803BN, AMVC960804CN, AMVC961005CN, AMVC961005DN, AMVC961205DN, ACVC960403BN, ACVC960603BN, ACVC960804CN, ACVC961005CN, ACVC961205DN
GMVM97 / GCVM97 / AMVM97 / ACVM97GMVM970603BN, GMVM970803BN, GMVM970804CN, GMVM971005CN, GMVM971205DN, AMVM970603BN, AMVM970803BN, AMVM970804CN, AMVM971005CN, AMVM971205DN
GRVM97 / GDVM97GRVM970603BN, GRVM970803BN, GRVM970804CN, GRVM971005CN, GRVM971205DN
GRVT80 / GDVT80GRVT800603BN, GRVT800603BX, GRVT800604BN, GRVT800604BX, GRVT800803BN, GRVT800804CN, GRVT800804CX, GRVT800805CN, GRVT800805CX, GRVT800805DN, GRVT800805DX, GRVT801005CN, GRVT801005CX, GDVT800603BX, GDVT800803BX, GDVT800805CX, GDVT801005CX
GRVT96 / GDVT96GRVT960403BN, GRVT960603BN, GRVT960803BN, GRVT960804CN, GRVT961005CN, GRVT961005DN, GRVT961205DN

Where this comes from

Checked against the manufacturer's manual on 13 October 2026.

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Other Goodman gas furnace codes

Code Meaning What you can do
EEL Igniter circuit problem Call a pro
EEn Igniter open Call a pro
EF Condensate blockage (depends on model) Call a pro
IF Internal control board fault Call a pro
1 amber flash Low-stage heat call You can often fix it
2 amber flashes High-stage or single-stage heat call You can often fix it
1 green flash Low-stage cooling call You can often fix it
2 green flashes High-stage or single-stage cooling call You can often fix it
green light flashing rapidly Fan-only call You can often fix it
steady green light Standby, waiting for a call You can often fix it
steady red light Normal operation or control board internal fault (depends on model) Depends on your model
On Normal operation You can often fix it

See all normal operation codes on gas furnaces across brands.