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Error code reference

Kenmore Dryer Error Code F-42

Motor control detects a voltage less than 90 VAC (undervoltage failure).

Kenmore codesKenmore dryer codes

Motor control detects a voltage less than 90 VAC (undervoltage failure).

First step from the service manual

See TEST #1 and DIAGNOSTIC: Displaying Line Voltage.

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

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What F-42 means on a Kenmore dryer

The F-42 error code on a Kenmore dryer indicates that the motor control board has detected an undervoltage condition, specifically a supply voltage reading below 90 VAC on the line coming into the unit. Electric dryers require a dedicated 240 VAC circuit (two legs of 120 VAC each) to operate correctly. The motor control monitors incoming line voltage continuously, and when either leg drops below the acceptable threshold, the control triggers F-42 to protect the motor and drive components from operating under damaging low-voltage conditions.

The most common sources of this fault are problems upstream of the dryer itself: a failing circuit breaker that has lost one leg of the 240 VAC supply, a loose or corroded connection at the terminal block where the dryer's power cord attaches, or a deteriorating power cord with high resistance at one of the hot conductors. In some cases, a utility-side issue can cause temporary voltage sags that trigger the code intermittently. The motor control board itself can also produce a false F-42 if its internal voltage sensing circuitry has failed, though this is a less likely cause than supply-side problems.

Diagnosing this code begins with the procedures outlined in TEST #1 and the DIAGNOSTIC: Displaying Line Voltage routine, which allow a technician to read the actual incoming voltage the control is seeing. Using a multimeter at the terminal block to confirm true supply voltage is an essential early step, since it separates a genuine power supply deficiency from a faulty motor control board that is misreading an otherwise adequate supply.

Source: manufacturer service documentation.

Common causes of F-42

  1. 01

    Tripped or failing circuit breaker

    Part replacement

    A 240 VAC dryer circuit uses a double-pole breaker. If one pole trips or weakens internally, the dryer receives only half the required voltage, immediately triggering F-42. Check the breaker panel for a partially tripped breaker and test each leg with a multimeter.

  2. 02

    Loose or corroded terminal block connection

    Wiring / connection

    The power cord connects to the dryer through a terminal block at the rear of the unit. A loose screw or corroded lug on one of the hot terminals creates resistance that drops voltage below 90 VAC under load. Inspect all terminal block connections for signs of arcing, discoloration, or looseness.

  3. 03

    Damaged or high-resistance power cord

    Part replacement

    A power cord with a damaged conductor, a cracked plug prong, or a loose prong-to-wire connection inside the plug can restrict current and reduce line voltage to the control board. Inspect the cord and plug for visible damage and measure resistance across each hot conductor.

  4. 04

    Utility or household wiring voltage sag

    Wiring / connection

    Low voltage from the utility supply or undersized household wiring can cause the incoming voltage to drop below 90 VAC, especially when other large loads are running. If the fault is intermittent, measure voltage at the outlet under load conditions to rule out a wiring or utility issue.

  5. 05

    Faulty motor control board

    Part replacement

    If the supply voltage measures correctly at the terminal block but F-42 persists, the motor control board's internal voltage sensing circuit may have failed and is reporting a false undervoltage condition. This is the least common cause and should only be concluded after confirming adequate line voltage.

See the test procedure for each cause

Frequently asked questions about F-42

What does F-42 mean on a Kenmore dryer?
F-42 means the motor control board has detected a line voltage below 90 VAC, which is too low for the dryer to operate safely. Electric dryers require a full 240 VAC supply, and this code triggers when that voltage drops below the acceptable minimum. The fault is most often caused by a tripped circuit breaker, a loose terminal block connection, or a damaged power cord. Running the DIAGNOSTIC: Displaying Line Voltage routine and TEST #1 are the recommended first steps.
Can I fix the F-42 error code myself?
Some causes of F-42, such as a tripped breaker or a loose terminal block connection, can be addressed by a knowledgeable DIYer who is comfortable working with electrical components. However, work at the terminal block involves exposure to line voltage and should only be performed with the dryer fully unplugged. Diagnosing whether the problem is in the breaker, the cord, the terminal block, or the motor control board requires a multimeter and a systematic approach following the TEST #1 and line voltage diagnostic procedures.
Is it safe to keep using my dryer when F-42 is showing?
No, you should not attempt to run the dryer while F-42 is active. Operating a dryer motor under sustained undervoltage conditions can overheat motor windings and damage the motor control board. The dryer's control system triggers this fault specifically to prevent that damage. Leave the dryer off until the power supply issue has been identified and corrected.
Will resetting the dryer clear the F-42 error?
A power cycle may temporarily clear the fault display, but F-42 will return as soon as the motor control detects the undervoltage condition again during operation. Because the root cause is an electrical supply problem rather than a software glitch, resetting alone does not fix anything. The underlying supply issue must be corrected before the code will stay cleared.
How much does it cost to repair an F-42 error on a Kenmore dryer?
Repair cost depends heavily on the root cause. Tightening a loose terminal block connection costs nothing beyond the time to diagnose it. Replacing a power cord typically runs in the range of $20 to $60 for the part, plus labor if a technician is involved. A circuit breaker replacement at the panel may cost $50 to $200 depending on the breaker type and whether an electrician is needed. If the motor control board itself has failed, board replacement parts generally range from $80 to $250, with additional labor costs if professionally repaired.

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