mypros+
Error code reference

Fisher & Paykel Dishwasher Error Code F21

Motor bridge over temperature fault.

Fisher & Paykel codesFisher & Paykel dishwasher codes

Motor bridge over temperature fault.

First step from the service manual

Check if the harness is connected correctly and inspect for water damage, corrosion, or arcing at motor and motor controller connections.

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

MyPros+ Max

Get the full diagnostic procedure for F21.

  • 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 F21 means on a Fisher & Paykel dishwasher

The F21 error code on a Fisher & Paykel dishwasher indicates a motor bridge over temperature fault. The motor bridge refers to the H-bridge circuit within the motor controller, which is responsible for driving the wash motor by switching current direction and controlling motor speed. When the temperature of this bridge circuit exceeds its safe operating threshold, the controller triggers the F21 fault to protect the components from thermal damage. This is a protective shutdown, not simply a sensor misread.

The most common root cause is a wiring or connection issue between the motor and the motor controller. Damaged harness connectors, corroded terminals, or arcing at connection points can increase electrical resistance, causing localized heat buildup in the bridge circuit. Water intrusion into the motor or controller connections is a particularly frequent contributor, since dishwashers operate in a high-humidity environment and any seal failure can expose electrical components to moisture.

In some cases, the fault can point to a failing wash motor drawing excessive current, which forces the bridge transistors to dissipate more heat than they are rated for. A motor that is mechanically binding, has degraded windings, or is beginning to fail will place an abnormal load on the controller circuit. Inspecting the harness and all connectors for physical damage, corrosion, or signs of arcing should always be the first step before replacing any components.

Source: manufacturer service documentation.

Common causes of F21

  1. 01

    Corroded or damaged motor harness connectors

    Wiring / connection

    Moisture and heat inside the dishwasher can corrode the terminals connecting the motor to the controller, increasing resistance and generating excess heat in the bridge circuit. Inspect all connectors for greenish or white corrosion, pitting, or loose pins.

  2. 02

    Water damage or arcing at motor or controller connections

    Part replacement

    Water intrusion into the motor or motor controller connection points can cause short circuits or arcing, which rapidly overheats the bridge components. Look for burn marks, melted plastic, or moisture residue around the connectors.

  3. 03

    Incorrectly seated or disconnected harness

    Wiring / connection

    A harness plug that is not fully seated at the motor or controller can create intermittent contact and localized resistance heating. Check that all connectors click fully into place and that no pins are pushed back or bent.

  4. 04

    Failing or seized wash motor

    Part replacement

    A wash motor that is mechanically binding or has deteriorating windings draws excessive current, overloading the motor bridge circuit and causing it to overheat. If connections check out clean and secure, testing motor current draw or inspecting for physical binding is the next step.

  5. 05

    Faulty motor controller

    Part replacement

    If the harness, connectors, and motor all test correctly, the motor controller itself may have internal bridge transistors that have degraded and can no longer handle normal operating temperatures. This is typically a last-resort diagnosis after all wiring and motor checks are completed.

See the test procedure for each cause

Frequently asked questions about F21

What does F21 mean on a Fisher & Paykel dishwasher?
F21 on a Fisher & Paykel dishwasher indicates a motor bridge over temperature fault. The motor controller has detected that its internal bridge circuit, which drives the wash motor, has exceeded a safe temperature limit and shut down to prevent damage. This is a protective fault code, not a routine operational error. It requires inspection of the motor wiring, connectors, and potentially the motor or controller itself.
Can I fix the F21 error myself, or do I need a technician?
Some causes of F21 are DIY-accessible, particularly inspecting and reseating harness connectors or cleaning corroded terminals at the motor connections. However, if you find arcing damage, water intrusion into the controller, or suspect a failing motor, those repairs typically require component replacement and a higher level of comfort working with appliance electronics. If you are unsure about safely accessing the motor and controller, a qualified appliance technician is recommended.
Will resetting the dishwasher clear the F21 error code?
A reset may temporarily clear the F21 code, but if the underlying cause is not addressed, the fault will return once the motor bridge overheats again during operation. Resetting is useful to confirm whether the fault is intermittent or persistent, but it should not substitute for a proper inspection of the motor harness, connectors, and related components.
Is it safe to use the dishwasher when F21 is showing?
It is not advisable to continue running the dishwasher while the F21 fault is active. The code indicates that the motor controller circuit has overheated, and continued operation without resolving the cause could lead to further damage to the motor controller or create an electrical hazard, particularly if water intrusion or arcing is involved. Stop use until the fault is diagnosed and corrected.
How much does it cost to repair an F21 error on a Fisher & Paykel dishwasher?
Repair costs vary depending on the root cause. If the fix is limited to cleaning corroded connectors or reseating a harness, costs may be minimal beyond a service call fee, typically in the range of $75 to $150. If the motor or motor controller requires replacement, parts and labor combined can range from $200 to $500 or more, depending on parts availability and local labor rates.

Related Fisher & Paykel dishwasher codes

All Fisher & Paykel dishwasher codes
View all 51 Fisher & Paykel dishwasher codes

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

Get Started

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