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Error code reference

Goodman Heat Pump Error Code E5

Open fuse

Goodman codesGoodman heat pump codes

Open fuse - short in low voltage wiring.

First step from the service manual

Locate and correct short in low voltage wiring. Replace fuse with 3-amp automotive type.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E5 means on a Goodman heat pump

The E5 error code on a Goodman heat pump indicates an open (blown) fuse in the low voltage control circuit. The low voltage system in a heat pump typically operates at 24 volts AC and powers the control board, thermostat, and all associated relays and contactors. A fuse in this circuit protects against current surges caused by wiring faults. When the fuse opens, the control board loses power or loses the ability to complete control circuits, triggering the E5 fault.

The root cause of a blown low voltage fuse is almost always a short circuit somewhere in the 24-volt wiring. This can occur at the thermostat terminals, in the thermostat wire run between the air handler or furnace and the outdoor unit, or at any point where wiring has been pinched, abraded, or improperly connected. The fuse itself is a 3-amp automotive type, which is a standard blade-style fuse commonly found at auto parts stores. Simply replacing the fuse without locating and correcting the short will result in the new fuse blowing immediately or shortly after startup.

Diagnosis requires a systematic inspection of the entire low voltage wiring path. Technicians should check for pinched wires at cabinet entry points, damaged insulation along the wire run, and incorrect wiring connections at the thermostat sub-base and control board terminals. A short to ground or a wire-to-wire short will cause immediate fuse failure. Once the fault is corrected, the fuse replacement should hold and normal operation should resume.

Source: manufacturer service documentation.

Common causes of E5

  1. 01

    Short circuit in thermostat wiring

    Wiring / connection

    The thermostat wire run between the indoor unit and the heat pump is the most frequent source of shorts, often caused by pinched, abraded, or staple-damaged insulation allowing bare conductors to contact each other or a grounded surface. Inspect the full wire run carefully for any physical damage.

  2. 02

    Incorrect thermostat wiring connection

    Wiring / connection

    Miswired terminals at the thermostat sub-base or the control board can create a direct short. Check that each wire matches the correct terminal designation at both ends of the thermostat cable.

  3. 03

    Blown 3-amp fuse requiring replacement

    Part replacement

    Once the short is located and corrected, the open fuse must be replaced with a 3-amp automotive blade-type fuse. Using a higher-amperage fuse will not protect the circuit properly and can cause further damage.

  4. 04

    Wire pinched at cabinet or conduit entry point

    Wiring / connection

    Low voltage wires routed through sheet metal cabinet knockouts or conduit fittings can have their insulation cut or worn through over time, creating a short to the grounded cabinet. Inspect all points where wires pass through or across metal edges.

  5. 05

    Failed accessory or control board component causing overcurrent

    Wiring / connection

    Accessories connected to the 24-volt circuit, such as zone controllers or humidistats, can develop internal shorts that pull excess current and blow the fuse. Disconnect any added accessories and check if the fuse holds before reinstalling them one at a time.

See the test procedure for each cause

Frequently asked questions about E5

What does E5 mean on a Goodman heat_pump?
The E5 code on a Goodman heat pump means the low voltage control circuit fuse has blown due to a short in the low voltage wiring. The low voltage system runs at 24 volts and controls the thermostat, relays, and control board functions. The unit will not operate normally until the short is found, corrected, and the 3-amp fuse is replaced.
Can I reset the E5 error code without fixing the wiring?
Resetting the unit or simply replacing the fuse without correcting the underlying short will not clear the E5 code permanently. The new fuse will blow again as soon as the circuit is re-energized with the short still present. The wiring fault must be located and repaired first for the repair to hold.
Is it safe to run my Goodman heat pump with an E5 error?
The heat pump will not operate while the fuse is open, so it is effectively locked out of normal operation. You should not attempt to bypass the fuse or install a higher-amperage fuse, as this removes protection from the low voltage wiring and control components and could cause further damage or a fire hazard.
How much does it cost to repair an E5 error on a Goodman heat pump?
If the repair only involves finding a pinched or miswired low voltage wire and replacing the 3-amp fuse, costs are typically in the range of $75 to $200 for a service call. If a control board or thermostat was damaged by the short and needs replacement, costs can rise to the range of $250 to $600 or more depending on the components involved.
What type of fuse does a Goodman heat pump use for the low voltage circuit?
Goodman specifies a 3-amp automotive blade-type fuse for the low voltage control circuit. This is a standard fuse available at auto parts stores and many hardware retailers. Always replace with the correct 3-amp rating, as installing a higher-rated fuse will defeat the circuit protection the fuse is designed to provide.

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