Goodman Error Code CoreSense 9: Red 9 flashes – PROT output overcurrent (Heat Pump)

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

Goodman error code CoreSense 9 on a heat pump means: Red 9 flashes - PROT output overcurrent. It is also called Goodman diagnostic code CoreSense 9.

High severityHeat PumpGoodman/Amana R-32 GLZS/ALZS · Goodman/Amana R-410A GSZ/ASZ/DSZ (ANZ/SSZ/VSZ)

Homeowner? What Goodman code CoreSense 9 means for you

Call a technician Your heat pump is reporting: Red 9 flashes - PROT output overcurrent. The heat pump has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.

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.
Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
In winter, keep snow and ice off and away from the outdoor unit. A short defrost cycle with steam is normal.
Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Goodman error code CoreSense 9 mean?

The module saw more than 2 A on its PROT (protection output) terminal for 40 ms and shut the output off. The manual gives only this definition.

Applies to: Copeland CoreSense 3-wire module: Amana/Deluxe R-410A ASX, ASZ, DSX, DSZ units and Amana R-32 ALXS / ALZS units

Common causes of Goodman code CoreSense 9

Overload or short on the circuit fed by the PROT terminal (manual gives no further causes)

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.

Goodman models that use code CoreSense 9

Show all 122 models

ALZS4BA**10AA ALZS4NA**10AA ALZS5BA**10AA ANZ130181 ANZ130241 ANZ130301 ANZ130361 ANZ130421 ANZ130481 ANZ130601 ANZ140181 ANZ140241 ANZ140301 ANZ140361 ANZ140421 ANZ140481 ANZ140491 ANZ140601 ASZ130181 ASZ130241 ASZ130301 ASZ130361 ASZ130421 ASZ130481 ASZ130601 ASZ140181 ASZ140241 ASZ140301 ASZ140361 ASZ140381 ASZ140421 ASZ140481 ASZ140491 ASZ140601 ASZ160181 ASZ160241 ASZ160301 ASZ160361 ASZ160421 ASZ160481 ASZ160601 ASZ180361 ASZ180481 ASZ180601 ASZH5***10 DSZ160241 DSZ160361 DSZ160481 DSZ160601 DSZ180361 DSZ180481 DSZ180601 GLZS4BA**10AA GLZS4MA**10AA GLZS5BA**10AA GSZ110903 GSZ110904 GSZ111203 GSZ111204 GSZ130181 GSZ130191 GSZ130241 GSZ130251 GSZ130301 GSZ130311 GSZ130361 GSZ130363 GSZ130371 GSZ130421 GSZ130481 GSZ130483 GSZ130484 GSZ130601 GSZ140181 GSZ140241 GSZ140301 GSZ140361 GSZ140371 GSZ140421 GSZ140481 GSZ140491 GSZ140601 GSZ160181 GSZ160241 GSZ160301 GSZ160361 GSZ160421 GSZ160481 GSZ160601 GSZH5***10 SSZ140181 SSZ140191 SSZ140241 SSZ140251 SSZ140301 SSZ140311 SSZ140361 SSZ140371 SSZ140381 SSZ140421 SSZ140481 SSZ140601 SSZ160241 SSZ160361 SSZ160421 SSZ160481 SSZ160601 VSZ130181 VSZ130241 VSZ130301 VSZ130361 VSZ130421 VSZ130481 VSZ130601 VSZ140181 VSZ140241 VSZ140301 VSZ140361 VSZ140421 VSZ140481 VSZ140491 VSZ140601

Other Goodman Heat Pump codes

Code	Meaning
b9	Indoor airflow lower than requested
CoreSense 1	Yellow 1 flash - long run time (low side)
CoreSense 2	Pressure trip - yellow 2 flashes (red 2 = lockout)
CoreSense 3	Short cycling / pressure switch cycling - yellow 3 (red 3 = lockout)
CoreSense 4	Locked rotor - yellow 4 (red 4 = lockout)
CoreSense 5	Moderate run trip - yellow 5 (red 5 = lockout)
CoreSense solid red	Solid red TRIP - call present but compressor not running
d0	No shared data on the network
d1	Invalid shared data on the network
d2	System mismatch - indoor unit cannot supply required airflow
d3	Configuration mismatch - shared data does not match hardware
d4	Shared data from the loader rejected

All Goodman Heat Pump error codes →

Goodman code CoreSense 9: homeowner questions

What does Goodman code CoreSense 9 mean?

Red 9 flashes - PROT output overcurrent. The module saw more than 2 A on its PROT (protection output) terminal for 40 ms and shut the output off. The manual gives only this definition.

Is it safe to keep using my heat pump with code CoreSense 9?

It depends on the cause. The heat pump has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.

Can I reset Goodman code CoreSense 9 myself?

You can try one reset (power off for 30 seconds, then on). If Goodman code CoreSense 9 comes back, the cause is still there and a licensed technician should check it.

Who can fix Goodman code CoreSense 9 near me?

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

Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air

Troubleshooting guides

No heat - R-32 GLZS/ALZS heat pump Goodman · Heat Pump
Outdoor coil iced / no defrost - R-32 GLZS/ALZS heat pump Goodman · Heat Pump
Reversing valve not shifting - ComfortNet heat pumps Goodman · Heat Pump

Source: Goodman RS6200301 R-32 GLXS/ALXS/GLZS/ALZS service (07-2024), CoreSense Diagnostics Table p.21-22 and Quick Reference Table p.23; Goodman RS6200006r103 R-410A ASX/GSX/DSX/ASZ/GSZ/DSZ service (text export) (Goodman_R_410A_ASX_GSX_DSX_A_C_and_ASZ_GSZ_DSZ_HP_covers_GSX_GSZ_lines_GSXH5_GSZH5_service.txt section Diagnostics Table: Coresense Module / Table 1 Quick Reference). 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.