Goodman Heat Pump Error Codes List: Every Code Explained
Every Goodman heat pump error code we could verify against Goodman's own documentation — what it means, what usually causes it, and the first fix to try — in one table. Codes differ between model series, so treat your model's tech sheet as the final word.
How to read and retrieve error codes on Goodman heat pumps
The outdoor integrated control module carries a 7-segment LED display (two characters, shown alternating) that displays the active code — 01, 02, A2, L1 and the rest of the table — with an arrow printed beside it marking the top of the display so characters are read the right way up. On a fully communicating ComfortNet system the same event is mirrored at the thermostat as a message (for example 'LOW SIDE FAULT' for 01, 'OUTDOOR AIR TEMP SENSOR FAULT' for A2) with a 'Call for Service' indication. Codes marked with an asterisk in Goodman's list are heat-pump-only (A3, the dF/dt/dE defrost displays, the P heat-mode indications). The d0–d4 family is not a unit fault at all: it reports shared-data problems on the communicating network (no data yet, invalid data, system or configuration mismatch, invalid memory card), fixed by populating the correct shared data with the model's memory card.
The complete Goodman heat pump error code list
| Code | Meaning | Most likely cause | First fix |
|---|---|---|---|
| 01 | Low pressure cut-out trip / low side fault — the low pressure switch has opened (ComfortNet thermostat message: LOW SIDE FAULT / LPS OPEN) | Low refrigerant charge, a restriction in the liquid line, indoor blower motor failure, or the thermostat set extremely low (Goodman's listed causes) | Check the indoor filter and that the indoor blower runs; charge verification, restriction repair and switch replacement are certified-technician work. Three trips in one demand become lockout L1 |
| 02 | High pressure cut-out trip / high side fault — the high pressure switch has opened (also the code shown after four consecutive compressor protector trips with average run time between 1 and 15 minutes, with both pressure switches closed) | Blocked condenser (outdoor) coil or an outdoor fan not running — Goodman's listed causes; in heating the same trip family covers a blocked indoor coil/airflow path | Clean the outdoor coil and confirm the outdoor fan runs and its capacitor is sound. The fault clears after four consecutive normal cycles, or by cycling 24 VAC to the control. Three switch trips in one demand become lockout L2 |
| 04 | Locked rotor — the control has detected a compressor locked-rotor condition | A compressor that cannot start turning: mechanical seizure, or a start circuit/capacitor failure imitating one | Technician work: start components and compressor diagnosis. Do not keep re-trying starts against a locked rotor |
| 06 | Open start circuit — current is present in the run circuit but not in the start circuit | A failed start capacitor/relay, or open wiring in the compressor start circuit | Technician start-circuit diagnosis. Repeated occurrences in one call become lockout L6 |
| 07 | Open run circuit — current is present in the start circuit but not in the run circuit | Open run winding circuit: wiring, capacitor or compressor run-winding failure | Technician diagnosis, as for 06. Repeated occurrences become lockout L7 |
| 08 | No line voltage — the control detects no line voltage at the unit | Disconnect open, breaker tripped, or supply wiring to the outdoor unit interrupted | Check the outdoor disconnect and breaker; supply-wiring faults are electrician/technician work |
| 09 | Low pilot voltage — the low-voltage (24 V) supply to the control is below its operating threshold | An overloaded or failing control transformer, or a partial short dragging the 24 V circuit down | Technician low-voltage diagnosis; a control starved of pilot voltage misbehaves in ways that imitate board failure |
| A2 | Outdoor air temperature sensor fault (ComfortNet message: OUTDOOR AIR TEMP SENSOR FAULT) | Open sensor, disconnected sensor, shorted sensor, or a sensor reading out of range | Check the sensor connection; replace an open/shorted sensor (Goodman's stated actions). Power OFF before repair |
| A3 | Outdoor coil temperature sensor fault (heat-pump models only) — the sensor that informs defrost decisions | Open, disconnected, shorted or out-of-range coil sensor | Check the connection and replace the sensor as for A2. Expect defrost behaviour to degrade while the coil sensor is unreadable |
| E5 | Open fuse — the control's low-voltage fuse has opened (ComfortNet message: FUSE OPEN / INTERNAL FAULT family) | A short in the low-voltage wiring (Goodman's listed cause) | Locate and correct the short first, then replace the fuse with a 3-amp automotive type (Goodman's stated actions). A fuse replaced into a live short opens again |
| EE | Board misoperation — the integrated control module has an internal fault (Goodman's troubleshooting tables pair EE with compressor relay contacts welded and control internal faults) | Internal failure of the outdoor integrated control module | Replace the control module with the correct replacement part, power OFF before repair (Goodman's stated action) |
| L1 | LPCO lockout — the low pressure switch has tripped three times within the same thermostat demand, and the control has locked the compressor out | The code 01 family persisting: low charge, liquid-line restriction, indoor blower failure or an extreme thermostat setting | Must be cleared by cycling 24 VAC to the control — but only after the 01 cause is fixed; Goodman's actions are charge verification, restriction repair, blower check and switch check |
| L2 | HPCO lockout — the high pressure switch has tripped three times within the same thermostat demand | The code 02 family persisting: blocked outdoor coil or a dead outdoor fan most often | Clean the coil, prove the fan, then clear by cycling 24 VAC to the control; a lockout cleared without its cause returns on the next demand |
| L6 | Open start circuit lockout — the open-start-circuit condition (06) has repeated enough in one call for the control to lock out | A failed start capacitor/relay or open start-circuit wiring that did not heal between attempts | Technician start-circuit repair before the lockout is cleared; repeated locked-rotor-style starts damage compressors |
| L7 | Open run circuit lockout — the open-run-circuit condition (07) has repeated into lockout | Open run-circuit wiring, capacitor failure or a compressor run-winding fault | Technician diagnosis as for 07, before clearing the lockout |
| L8 | Low line voltage — the supply voltage at the unit is low (the voltage counterpart of 09's low pilot voltage) | Utility sag, a failing disconnect/contactor, or supply wiring dropping voltage under compressor load | Verify line voltage under load. Recurring low voltage is electrician/technician work — compressors started on low voltage overheat |
| P0 | Compressor protector open (heat pump models) — the compressor's protector has opened while a demand is present | Compressor overheating or an electrical condition that opened its internal/external protector | Let the compressor cool fully before any restart attempt; the reason it overheated (charge, airflow, voltage) is technician diagnosis |
| b0 | No indoor airflow — the circulator blower motor is not running when it should be (fully communicating systems) | Indoor blower motor problem, a welded compressor relay contact confusing the control, or a communication error between the indoor and outdoor units (Goodman's listed causes) | Check the indoor blower motor, its wiring and the indoor unit control; repair/replace faulty wiring, motor or control (Goodman's stated actions) |
| b9 | Inadequate airflow — indoor airflow is lower than demanded | Blocked filters, restrictive or undersized ductwork, or an indoor/outdoor unit mismatch (Goodman's listed causes) | Clean/replace filters and correct duct restrictions; verify the indoor and outdoor units are an approved match |
| dE | Forced defrost — a heat pump model has been put into defrost deliberately (test/forced mode) rather than by the defrost control's own decision | A technician forcing a defrost to test the cycle, or the control left in/returning from a test state | No repair needed if a service visit explains it. A unit that repeatedly sits in forced defrost on its own needs control diagnosis |
| dF | Defrost — a status display on heat pump models, not a fault: the unit is in a defrost cycle | Normal winter operation: the defrost control has found the outdoor coil cold enough (defrost thermostat closed at its check) to need defrosting | No repair needed. During defrost the outdoor fan stops, the reversing valve shifts and auxiliary heat (W2) is energised to temper the indoor air — steam from the outdoor unit and cooler vent air are normal |
| dt | Max defrost time — a defrost cycle on a heat pump model has run to its maximum-time limit (Goodman's defrost board terminates a defrost at the programmed 10-minute override if the defrost thermostat has not opened first) | A defrost that could not raise the coil temperature in time: very heavy frost/ice load, low charge, or a defrost thermostat/sensor that never registers warm | An occasional dt in severe icing weather is the override doing its job. dt on every defrost is technician territory — charge, sensor and reversing-valve checks |
How to reset / clear error codes on Goodman heat pumps
Goodman's communicating control separates trips from lockouts. Single cut-out trips (01 low pressure, 02 high pressure) clear on their own evidence — the 02 fault, for example, clears after four consecutive normal cycles, or immediately by cycling 24 VAC to the control. Three trips of the same pressure switch within one thermostat demand become a lockout (L1 low pressure, L2 high pressure), and Goodman's tables state the lockout must be cleared by cycling 24 VAC to the control — after the cause is repaired. Start/run circuit faults escalate the same way (06→L6, 07→L7). Cycling the 24 V is done at the indoor air handler/furnace power, not by pulling the outdoor disconnect repeatedly.
How to diagnose any Goodman heat pump code
Work the problem in this order — and stop where the refrigerant circuit, the compressor or mains wiring begins, because those belong to a licensed HVAC technician with gauges: (1) record the code exactly, and note where it appeared — the outdoor board's LED, a communicating wall control, or an app — because one heat pump can report the same fault three different ways; (2) run the free checks first: the air filter is clean, the indoor coil is not iced over, the outdoor unit is clear of leaves, snow and debris, both breakers are on, and the condensate drain is not lifting a float switch; (3) remember that defrost is not a fault — in cold weather the outdoor fan stops, the unit steams and hisses and the indoor air cools for a few minutes while frost melts off the outdoor coil; a defrost that never ends, or ice that never clears, is the fault, not the defrost itself; (4) clear the code once and watch a full heating cycle from the start — the stage that stops (outdoor fan, compressor, defrost, auxiliary heat) names the fault family; (5) pressure lockouts, reversing-valve faults and compressor faults are diagnosed with gauges and a meter on the sealed circuit — never "top up" refrigerant to make a code go away, because a heat pump losing charge has a leak, and the code is protecting the compressor from it.
Goodman defrost in two dialects: the defrost thermostat that checks every 30, 60 or 90 minutes, and the ComfortNet display that narrates it
Most Goodman heat pumps ever installed defrost by appointment. Goodman's DSZ service manual describes the classic arrangement plainly: the defrost control checks whether a defrost is needed every 30, 60 or 90 minutes of heat-pump operation, depending on a selectable setting, by monitoring a defrost thermostat attached to the outdoor coil. Only if the coil is cold enough for that thermostat to be closed at check time does a cycle begin. When it does, the choreography is fixed: the defrost board's HVDR relay opens and stops the outdoor fan, the LVDR relay closes and supplies 24 V to 'O' and 'W2' — energising the reversing valve (shifting the unit briefly into cooling) and the first stage of electric auxiliary heat, so the air from the vents stays tempered while the coil melts. Termination is equally mechanical: when the coil warms enough to open the defrost thermostat, the cycle ends; if the thermostat is still closed at the end of the programmed 10-minute override, the board terminates the defrost anyway. Then the relays swap back, the fan restarts, the reversing valve and heaters drop out, and normal heating resumes. That 10-minute override is the fact that decodes the communicating generation's dt display ('max defrost time'): dt does not mean the defrost failed, it means it was ended by the clock rather than by the thermostat — normal in a hard icing event, suspicious as an every-cycle habit. The ComfortNet generation narrates the same physical cycle on its 7-segment display: dF while defrost runs, dE when a defrost has been forced (a technician's test, or the control's own forced routine), dt at maximum time. Those three are status displays, marked heat-pump-only in Goodman's list, and owners who read them as faults generate needless service calls every winter. The genuine defrost-related faults on a communicating Goodman are the ones around the cycle rather than in it: A3, the outdoor coil temperature sensor fault, which removes the control's knowledge of coil temperature, and the pressure trips 01/02, which a coil buried in ice will eventually produce in heating. A non-communicating Goodman, by contrast, will tell you none of this: its defrost board has test pins and a thermostat, no display and no codes — a silent unit with a frosted coil is diagnosed with gauges and the documented sequence above, not with a code list, and any 'Goodman heat pump flash code' list that claims otherwise is describing a furnace or a different brand.
Auxiliary heat, staging and the trip-to-lockout ladder on a Goodman system
A Goodman heat pump does not work alone in winter; it is the first stage of a staged system, and Goodman's own service manual walks the stages in order. First-stage heat demand (Y) runs the heat pump. If the second-stage demand (W2) cannot be satisfied by the heat pump, indoor temperature keeps falling until the thermostat energises W3, bringing on the second bank of electric heat through relay HR2; the manual even times the unwinding — when demands are satisfied in reverse order, the heater relays open after 30 to 70 seconds, and when the first-stage demand finally ends, the blower runs a 65-second off-delay before stopping. Two consequences matter for reading behaviour. First, auxiliary heat during defrost is not a malfunction: the defrost sequence itself energises W2, deliberately, every cycle. Second, a heat pump in a pressure lockout does not leave the house cold — the thermostat simply lives on its W2/W3 stages, and the only visible symptom is a power bill. That is why Goodman's trip-to-lockout ladder deserves respect rather than resets. On the communicating control, a single low-pressure trip (01) or high-pressure trip (02) is a report with named causes — low charge, a liquid-line restriction or indoor blower failure for 01; a blocked outdoor coil or a stopped outdoor fan for 02. The 02 fault even clears itself after four consecutive normal cycles. But three trips of the same switch inside one thermostat demand become a lockout (L1 or L2) that, per Goodman's tables, must be cleared by cycling 24 VAC to the control. The start/run circuit family climbs the same ladder (06 to L6, 07 to L7), and Goodman's cause lists keep pointing at unglamorous hardware: filters, duct restrictions, a blower that is not moving air, a fan capacitor. The seasonal pattern writes itself from those causes. Autumn's first cold weeks produce 01s from systems that leaked charge all summer; deep winter produces 02s in heating when indoor airflow cannot carry the delivered heat; and the lockouts arrive at the end of those stories, not the beginning. When a lockout is reported, the useful owner evidence is the ladder position — first trip or third, self-cleared or locked — plus which stage the house was actually heating on. 'It heats fine but the bill doubled' is an L1/L2 story until proven otherwise. Goodman's controls also keep receipts: the integrated control stores the last six faults, and a technician can recall them from standby by pressing the control's push-button for two to five seconds — the display sequences through the stored codes most-recent-first, with a code that repeated consecutively stored up to three times — while holding the button beyond five seconds clears the memory. That history is why a Goodman that 'fixed itself' still deserves its service visit read-out: the self-cleared 02 that happened four times last month is in there, and it is the difference between a control that forgives and a coil that is quietly matting over.
Related guides
Facts on this page were checked against manufacturer documentation: manualmachine.com · resource.ecmdi.com · hvacdirect.com · www.manualsdir.com