mypros+
Error code reference

Whirlpool Microwave Error Code ERR 1

Short circuit in the MW (microwave) relay.

Whirlpool codesWhirlpool microwave codes

Short circuit in the MW (microwave) relay.

MyPros+ Max

Get the full diagnostic procedure for ERR 1.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What ERR 1 means on a Whirlpool microwave

ERR 1 on a Whirlpool microwave indicates a short circuit condition detected in the microwave (MW) relay circuit. The MW relay is a high-voltage switching component responsible for controlling power delivery to the magnetron, which is the tube that generates the microwave energy used for cooking. When the control board detects an abnormal low-resistance or zero-resistance condition across the relay circuit, it interprets this as a short and halts operation to prevent component damage or a fire hazard.

A short circuit in the relay circuit can occur at several points: the relay itself may have welded or fused contacts, the wiring harness connecting the relay to the control board may have damaged insulation causing conductors to contact each other, or the magnetron load that the relay drives may have developed an internal short that reflects back through the circuit. Relay contact welding is common in microwaves that have experienced repeated high-load cycles or a voltage surge.

Because this fault involves high-voltage components, diagnosis requires extreme caution. Microwave capacitors can retain a lethal charge even after the unit is unplugged. A technician should discharge the high-voltage capacitor before probing any relay or magnetron circuit. The relay itself can be tested for shorted contacts using a continuity meter while the unit is unpowered, checking that the relay contacts show open circuit in the de-energized state.

Source: manufacturer service documentation.

Common causes of ERR 1

  1. 01

    Welded or fused relay contacts

    Part replacement

    The MW relay contacts can weld together due to arcing from voltage surges or repeated high-current switching, creating a permanent short across the circuit. A continuity check on the relay in its de-energized state will show continuity when it should show an open circuit.

  2. 02

    Shorted magnetron

    Part replacement

    An internal short in the magnetron can present as a short circuit load on the relay circuit, triggering ERR 1. The magnetron filament or internal structure may have failed, and resistance testing across the magnetron terminals will typically show a very low or near-zero reading.

  3. 03

    Damaged wiring harness

    Part replacement

    Insulation breakdown on the wiring between the relay and other high-voltage components can cause conductors to short together. Inspect the harness for burn marks, melted insulation, or pinched wires near sharp chassis edges.

  4. 04

    Faulty control board

    Part replacement

    If the relay driver circuit on the main control board has failed, the board may be incorrectly detecting or causing a short condition. This is less common but possible if the relay and wiring test normal.

See the test procedure for each cause

Frequently asked questions about ERR 1

What does ERR 1 mean on a Whirlpool microwave?
ERR 1 indicates the control board has detected a short circuit in the microwave relay circuit. The relay is the component that switches power to the magnetron, which generates the cooking energy. The microwave shuts down when this error appears to prevent further electrical damage or a potential fire hazard. The fault must be diagnosed and repaired before the unit can safely operate.
Can I fix ERR 1 on my Whirlpool microwave myself?
Repairing this error requires working near high-voltage components, including a capacitor that can hold a lethal charge even after the microwave is unplugged. DIY repair is not recommended unless you have specific experience discharging microwave capacitors and working with high-voltage circuits. A qualified appliance technician should perform the diagnosis and any relay, magnetron, or wiring repairs.
Is it safe to use my Whirlpool microwave while ERR 1 is displayed?
No, the microwave should not be used while ERR 1 is active. A short circuit in the relay circuit poses a risk of further component damage, overheating, or in severe cases, a fire. Keep the unit unplugged until the fault has been properly diagnosed and repaired.
Will resetting my Whirlpool microwave clear ERR 1?
A power reset by unplugging the unit may temporarily clear the error display, but it will not resolve the underlying short circuit condition. The fault is caused by a hardware problem such as a welded relay, shorted magnetron, or damaged wiring, and it will return as soon as the microwave attempts to operate again. A reset alone is not a fix.
How much does it cost to repair ERR 1 on a Whirlpool microwave?
Repair costs vary depending on which component has failed. Relay replacement is generally a lower-cost repair, while magnetron replacement is more expensive and can range into the $150 to $350 range including labor, depending on the model and service rates in your area. If the control board is the faulty component, costs can be higher. Getting a diagnostic estimate first will help you decide whether repair or replacement is the better value.

Related Whirlpool microwave codes

All Whirlpool microwave codes
View all 141 Whirlpool microwave codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass