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LG F42

LG Oven Error F42: Voltage Error — Supply Voltage Out of Range

Clear meaning, realistic next steps, and safe guidance without turning the page into a long repair manual.

What it means

The oven has detected that the incoming supply voltage is either too high or too low. Electric ranges require a stable 240V supply (two 120V legs) — a missing or weak leg will trigger F42.

Severity

High - stop using the LG oven until the cause is understood or professional help is arranged.

Can you fix it yourself?

Partial — start with DIY steps

Most likely cause

One leg of the 240V supply has dropped — a circuit breaker in a double-pole breaker has partially tripped

Estimated time for safe first checks: 5–10 min for breaker reset; Electrician visit if wiring fault.

Step-by-Step DIY Fix Guide

  1. SAFETY: Turn off the range and disconnect power at the circuit breaker.
  2. Locate the double-pole breaker for the range in the electrical panel. Flip it fully OFF then fully ON to reset — a partially tripped leg is the most common cause of F42.
  3. Confirm the range is plugged into a 240V outlet — a 240V outlet has four prongs (on newer installations) or three prongs on older wiring. A standard 120V outlet will not power the range correctly.
  4. Restore power and test a bake cycle.
  5. If F42 returns, call a licensed electrician to verify the 240V supply at the outlet with a multimeter — both legs should read approximately 120V each (240V total).

If the code comes back

  • F42 returns after resetting the circuit breaker
  • Both legs of the 240V supply are confirmed correct at the outlet but F42 persists — loose terminal block connection inside the range

What This Error Means

Error F42 on your LG oven means: The oven has detected that the incoming supply voltage is either too high or too low. Electric ranges require a stable 240V supply (two 120V legs) — a missing or weak leg will trigger F42. The range's self-diagnostic system has detected this condition.

The most frequent cause is one leg of the 240v supply has dropped — a circuit breaker in a double-pole breaker has partially tripped. Work through the causes and fix steps below in order — many LG oven errors are resolved without a service call.

Many cases of F42 can be resolved by the homeowner. The steps below cover the full DIY checks — if they do not resolve the error, a technician is needed.

Electric ranges require a stable 240V dedicated circuit. A partially tripped breaker — where one leg of the double-pole breaker has tripped but not the other — is a common and easily overlooked cause of voltage errors. Fully toggle the breaker off and on before investigating further.

Most Likely Cause by Symptom

The LG oven may stop, pause, or refuse to complete the cycle normally.

Likely cause: One leg of the 240V supply has dropped — a circuit breaker in a double-pole breaker has partially tripped

Check first: SAFETY: Turn off the range and disconnect power at the circuit breaker.

Common Causes

  • One leg of the 240V supply has dropped — a circuit breaker in a double-pole breaker has partially tripped
  • Range plugged into a 120V outlet instead of a 240V outlet — incorrect installation
  • Loose wire connection at the terminal block inside the range where the power cord connects
  • Utility-side voltage sag during high-demand periods

What Not to Do

  • Do not run the oven with F42 active — operating on a single 120V leg stresses the control board and can cause permanent damage

Model and Display Variation Notes

Model-family notes

  • LG oven display wording and code formats can vary by series.
  • If your model behaves differently, check the owner manual before trying any deeper maintenance step.

Display and panel differences

  • Panel wording can vary by series, so confirm the exact code pattern before buying parts.

Parts, Tools and Service Options

Service option

LG service visit if the warning returns after the basic checks are complete.

Manual and model check

Check your exact model and manual before ordering any LG oven parts.

This section stays service-first because the page points more strongly toward support or professional repair than a routine parts purchase.

When Not to Keep Troubleshooting

F42 returns after resetting the circuit breaker

  • Both legs of the 240V supply are confirmed correct at the outlet but F42 persists — loose terminal block connection inside the range

How to Prevent It Recurring

  • Have the range outlet inspected every 5 years — loose terminal connections at the outlet are a common cause of intermittent F42 errors on older installations

Related Error Codes

Extra notes

  • This page is based on LG support material and stays conservative where model-specific guidance may vary.
  • The goal is to help you identify safe first checks before you move into parts, service, or model-specific manual lookup.

Source and model notes

Last reviewed: 2026-04-08

Based on: Based on LG support material and edited into consumer-safe guidance for the exact code family on this page.

View LG US Official Support

Model coverage note: LG oven code meanings can vary by series, control panel, and model family, so use this page as a safe starting point rather than a replacement for the model-specific manual.

Important: FixThisError is an independent guide, not the manufacturer. Use your model-specific manual when the panel wording or behavior differs.

Always disconnect power before inspecting appliances. If unsure, contact a licensed appliance technician.