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Error code reference

Amana Microwave Error Code FH

High current detected from magnetron circuit.

Amana codesAmana microwave codes

High current detected from magnetron circuit.

First step from the service manual

Place oven in Service Test and isolate magnetrons using magnetron test; verify wire is routed through current sense loop.

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

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What FH means on a Amana microwave

The FH error code on an Amana microwave indicates that high current has been detected from the magnetron circuit. The magnetron is the core component responsible for generating microwave energy to heat food. It operates as part of a high-voltage circuit that includes the high-voltage transformer, capacitor, and diode. The control board monitors current flow through this circuit using a current sense loop, and when the measured current exceeds the expected threshold, the FH code is triggered as a protective shutdown.

The most common causes involve either a fault within the magnetron itself or a wiring issue affecting the current sense loop. A failed or degrading magnetron can draw excessive current, registering as an overcurrent condition. Equally important is the physical routing of the wire through the current sense loop: if this wire is incorrectly routed or bypasses the loop entirely, the control board may misread normal current as abnormally high, triggering a false FH fault.

Diagnosis requires placing the oven in Service Test mode and using the magnetron test function to isolate which magnetron or circuit is responsible for the fault. During this process, the technician should verify that all relevant wiring is correctly routed through the current sense loop. This step eliminates wiring routing errors before condemning the magnetron or other high-voltage components. Given the lethal voltages present in the high-voltage circuit, capacitor discharge procedures must be performed before any hands-on component inspection.

Source: manufacturer service documentation.

Common causes of FH

  1. 01

    Magnetron drawing excessive current

    Part replacement

    A failing or shorted magnetron can draw current beyond the normal operating range, triggering the FH code. This is identified through the magnetron test in Service Test mode.

  2. 02

    Wire not routed through current sense loop

    Wiring / connection

    If the sense wire is not correctly routed through the current sense loop, the control board receives an inaccurate current reading and may trigger a false FH fault. Visually inspecting the wire routing is a required diagnostic step.

  3. 03

    Damaged or shorted high-voltage wiring

    Part replacement

    Wiring in the high-voltage circuit that has become pinched, burned, or shorted can cause abnormal current readings. Inspect all wiring in the magnetron circuit for visible damage or melting.

  4. 04

    Faulty high-voltage diode or capacitor

    Part replacement

    A defective diode or capacitor in the high-voltage circuit can alter current flow in ways that register as overcurrent on the control board. These components should be tested after the magnetron and wiring have been inspected.

  5. 05

    Control board misreading current sensor

    Part replacement

    In some cases the control board itself may be misinterpreting the signal from the current sense circuit, particularly if the board has suffered a component failure. This is typically considered after all other causes have been ruled out.

See the test procedure for each cause

Frequently asked questions about FH

What does FH mean on a Amana microwave?
The FH code on an Amana microwave means the control board has detected high current from the magnetron circuit. The magnetron is the component that generates microwave energy to cook food, and it operates within a high-voltage circuit. When current in that circuit exceeds expected levels, the microwave shuts down and displays FH as a protective measure. Diagnosing this code requires Service Test mode and a check of the magnetron and current sense loop wiring.
Can I reset the FH error code on my Amana microwave?
Unplugging the microwave and restoring power may temporarily clear the FH code, but the fault will almost certainly return during the next heating cycle if the underlying problem is not resolved. A reset does not correct a failing magnetron or an incorrectly routed sense wire. Proper diagnosis using the magnetron test in Service Test mode is needed to prevent the code from reappearing.
Is it safe to use my Amana microwave when the FH code is showing?
You should not continue using the microwave while the FH code is active. The code indicates a high-current condition in the magnetron circuit, which can involve components operating at potentially lethal voltages. Continued use risks further damage to the appliance and poses a safety hazard. The microwave should remain unplugged until the fault is diagnosed and repaired by a qualified technician.
How much does it cost to fix an FH error on an Amana microwave?
Repair costs depend on the root cause identified during diagnosis. A magnetron replacement is typically the most expensive repair, with parts and labor costs often ranging from $150 to $350 or more depending on the model and service provider. Repairs involving only a wiring correction or a less expensive component such as a diode are generally on the lower end of the cost range. In some cases, the cost of repair may approach the cost of replacement, so obtaining a diagnosis first is advisable.
What does a technician check when diagnosing the FH code on an Amana microwave?
The technician begins by placing the microwave in Service Test mode and running the magnetron test to isolate the fault within the magnetron circuit. They also verify that the wire associated with the current sense circuit is correctly routed through the current sense loop, since improper routing can trigger a false FH reading. If both of those checks are normal, the high-voltage diode, capacitor, and wiring are inspected for damage. All high-voltage component work requires the capacitor to be safely discharged before hands-on testing.

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