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Error code reference

Amana Microwave Error Code LO

Low line voltage detected

Amana codesAmana microwave codes

Low line voltage detected – input voltage less than 185 VAC or inoperative low voltage board.

First step from the service manual

Instruct customer to unplug oven for one minute, reconnect, and retest. If error persists, check input voltage (less than 185 VAC) or replace inoperative low voltage board.

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

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What LO means on a Amana microwave

The LO error code on an Amana microwave indicates that the unit has detected input line voltage below 185 VAC. The microwave continuously monitors the incoming AC voltage supply, and when the voltage drops beneath this threshold, the control system triggers the LO fault to protect internal components from operating under insufficient power conditions. This is a protective measure to prevent damage to the magnetron, capacitor, and other high-voltage components that require stable input voltage to function safely and correctly.

The two primary sources of this fault are an actual low-voltage condition at the wall outlet or circuit supplying the microwave, and a failed low voltage board inside the unit. The low voltage board is responsible for stepping down and regulating power to the control electronics. If this board becomes inoperative, it may falsely report or fail to regulate voltage correctly, triggering the LO code even when the supply voltage is adequate. Distinguishing between these two causes requires measuring the actual voltage at the outlet with a multimeter.

A temporary voltage sag caused by grid fluctuations, a heavily loaded circuit, or a loose connection at the outlet or breaker panel can also trigger this error. In some cases, simply unplugging the microwave for one minute and reconnecting it clears the fault if the voltage condition was transient. If the error returns immediately, the technician should measure the supply voltage directly at the outlet before condemning the low voltage board.

Source: manufacturer service documentation.

Common causes of LO

  1. 01

    Low supply voltage at the outlet

    Wiring / connection

    The incoming AC voltage at the wall outlet or dedicated circuit is below 185 VAC. This can result from a heavily loaded circuit, a weak grid supply, or a loose connection at the breaker panel or outlet. Measure the outlet voltage with a multimeter while the microwave is connected.

  2. 02

    Inoperative low voltage board

    Part replacement

    The internal low voltage board has failed and is either not supplying correct regulated power to the control electronics or is incorrectly signaling a low voltage condition. If the outlet voltage measures within a normal range, this board is the likely cause and will need replacement.

  3. 03

    Transient voltage sag or power fluctuation

    Wiring / connection

    A brief dip in utility power, such as during high household demand or a momentary grid disturbance, can trigger the LO code. Unplugging the microwave for one minute and reconnecting it will often clear this type of fault if the voltage has since stabilized.

  4. 04

    Loose or degraded outlet connection

    Wiring / connection

    A loose outlet receptacle, corroded contacts, or a poor connection at the breaker can cause intermittent or sustained low voltage readings at the supply point. Inspect the outlet for secure fit and check the breaker connection in the panel.

  5. 05

    Undersized or shared circuit

    Wiring / connection

    If the microwave shares a circuit with other high-draw appliances, simultaneous operation can pull the available voltage below the 185 VAC minimum required. Microwaves ideally should operate on a dedicated circuit to avoid this condition.

See the test procedure for each cause

Frequently asked questions about LO

What does LO mean on a Amana microwave?
The LO error code means the microwave has detected that the incoming line voltage is below 185 VAC, or the internal low voltage board has failed. The unit triggers this fault to protect its components from operating under insufficient power. It can be caused by a real voltage problem at the outlet or by a failed board inside the microwave.
Will resetting the microwave clear the LO error code?
Unplugging the microwave for one minute and then reconnecting it is the recommended first step and can clear the code if the cause was a temporary power fluctuation. However, if the underlying issue is a persistent low supply voltage or a failed low voltage board, the LO code will return after the reset. Always retest after unplugging to determine if the fault is recurring.
How do I fix the LO error on my Amana microwave?
Start by unplugging the unit for one minute and reconnecting it. If the error returns, use a multimeter to check the voltage at the wall outlet and confirm it is above 185 VAC. If the outlet voltage is normal, the internal low voltage board is likely inoperative and will need to be replaced by a qualified technician. If the outlet voltage itself is low, the electrical supply circuit needs to be evaluated.
Is the LO error on an Amana microwave a safety concern?
Yes, operating a microwave on voltage below its rated minimum can stress internal components such as the magnetron and capacitor, potentially shortening their lifespan or causing further damage. The LO code is a protective fault designed to prevent the unit from running under these conditions. Do not attempt to bypass or ignore the error, and address the underlying voltage or board issue before continuing to use the microwave.
How much does it cost to repair an Amana microwave showing the LO code?
If the cause is simply a low supply voltage at the outlet, there may be little to no cost if the fix involves resetting a breaker or having an electrician tighten a connection, though electrical service calls typically range from $75 to $200. If the low voltage board inside the microwave needs replacement, parts and labor costs generally range from $100 to $250 depending on the service provider and part availability. In some cases, if the repair cost approaches the price of a new unit, replacement may be worth considering.

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