Find diagnostic mode instructions for washing machines, dryers, dishwashers, refrigerators, air conditioners, boilers, ovens, coffee machines, and other household appliances.

Diagnostic mode, sometimes called service mode, test mode, or troubleshooting mode, can help display stored fault codes and test selected appliance functions. It is mainly designed for technicians, so the correct procedure must be confirmed for the exact brand and model.

Do not enter diagnostic mode using a button sequence found for a different appliance. The wrong sequence may change settings, start a test unexpectedly, or place the appliance in a technician-only menu.

Find a Diagnostic Mode Guide

Use the search tool to find instructions for your appliance.

Search box placeholder:

Enter a brand, appliance, or model number

Search button:

Find Diagnostic Guide

Try searches such as:

• LG washer diagnostic mode
• Samsung washing machine test mode
• Whirlpool washer service mode
• Maytag dryer diagnostic mode
• Bosch dishwasher error code history
• GE refrigerator diagnostic mode
• Daikin air conditioner service mode
• De’Longhi coffee machine test mode

Include the full model number whenever possible. Diagnostic procedures can differ between models that look almost identical.

Browse Diagnostic Guides by Appliance

Washing Machine Diagnostic Mode

Washing machine diagnostic mode may help retrieve stored error codes or test functions such as:

• Water inlet
• Drain pump
• Door or lid lock
• Drum rotation
• Spin operation
• Temperature sensing
• Water-level sensing
• Motor response

Some machines run an automatic test cycle after diagnostic mode begins. Make sure the drum is empty and the appliance is safely connected before starting a verified test.

Browse Washing Machine Diagnostic Guides

Dryer Diagnostic Mode

Dryer diagnostic mode may provide information about:

• Stored fault codes
• Door switch status
• Temperature sensors
• Moisture sensors
• Motor operation
• Airflow warnings
• Heating-system faults
• Control-panel inputs

Do not bypass safety devices or run heating tests with panels removed.

Browse Dryer Diagnostic Guides

Dishwasher Diagnostic Mode

Dishwasher service or test mode may check:

• Water filling
• Drain operation
• Heating
• Leak detection
• Door latch status
• Temperature sensors
• Circulation pump operation
• Stored error history

Some diagnostic cycles may fill, heat, or drain automatically. Keep the door closed unless the manufacturer specifically instructs otherwise.

Browse Dishwasher Diagnostic Guides

Refrigerator Diagnostic Mode

Refrigerator diagnostic mode may test or display information about:

• Temperature sensors
• Evaporator and condenser fans
• Defrost system
• Ice maker
• Compressor control
• Door switches
• Display communication
• Stored error codes

Refrigerator service menus may include settings that affect cooling performance. Do not change technical values unless the manufacturer clearly identifies them as user-accessible.

Browse Refrigerator Diagnostic Guides

Air Conditioner Diagnostic Mode

Air conditioner diagnostic or service mode may display:

• Indoor unit faults
• Outdoor unit faults
• Sensor errors
• Fan motor problems
• Communication failures
• Compressor protection codes
• Stored error history
• Operating data

Air conditioning systems involve high voltage and refrigerants. Diagnostic information may help identify the fault area, but internal testing should be performed by a qualified HVAC technician.

Browse Air Conditioner Diagnostic Guides

Boiler and Furnace Diagnostic Mode

Heating systems may provide stored fault codes, operating status, pressure readings, ignition history, or combustion-related information.

Diagnostic menus may cover:

• Ignition faults
• Flame detection
• Water pressure
• Fan operation
• Temperature limits
• Pump status
• Thermostat communication
• Service history

Do not alter gas, combustion, fan, pressure, or flue settings. These adjustments require qualified heating professionals.

Browse Boiler and Furnace Diagnostic Guides

Oven and Microwave Diagnostic Mode

Service modes for ovens, ranges, and microwaves may test:

• Temperature sensors
• Control buttons
• Door switches
• Cooling fans
• Heating circuits
• Display functions
• Stored error codes
• Communication between control boards

Microwave ovens can retain dangerous electrical voltage even after being unplugged. Internal inspection should only be performed by trained professionals.

Browse Oven and Microwave Diagnostic Guides

Coffee Machine Diagnostic Mode

Coffee machine test modes may check:

• Water flow
• Pump operation
• Grinder response
• Temperature sensors
• Brew unit position
• Milk system
• Tray and container sensors
• Stored warnings

Do not change calibration values unless the procedure is verified for the exact model.

Browse Coffee Machine Diagnostic Guides

What Is Appliance Diagnostic Mode?

Diagnostic mode is a built-in troubleshooting function used to identify faults and test appliance systems.

Depending on the appliance, it may:

• Display active error codes
• Show stored fault history
• Test buttons and sensors
• Activate individual components
• Run an automatic test cycle
• Display operating values
• Confirm whether a part is responding
• Help a technician narrow down the fault

Diagnostic mode does not automatically identify the exact failed part. A code may point to a system with several possible causes.

For example, a drainage code may involve:

• A blocked filter
• A kinked hose
• A damaged pump
• Loose wiring
• A faulty pressure sensor
• A control-board problem

Diagnostic Mode, Service Mode, and Test Mode

Manufacturers may use different names for similar functions.

Diagnostic mode

Usually displays fault codes or tests appliance functions.

Service mode

May provide deeper technical controls intended for trained service personnel.

Test mode

Often runs a short automatic or manual component test.

Error history

Displays previously recorded faults, even when the appliance is currently operating.

Demo or showroom mode

Disables normal heating, cooling, or washing functions for display purposes. It is not a diagnostic mode.

Confirm which mode you are entering before pressing any buttons.

What to Do Before Entering Diagnostic Mode

Complete these checks first:

1. Record the exact error code shown.
2. Take a photograph of the display.
3. Confirm the appliance brand.
4. Find the complete model number.
5. Check the country or regional version.
6. Read the appliance manual.
7. Remove clothes, dishes, or loose items if a test cycle may start.
8. Check for leaks, smoke, sparks, gas smells, or overheating.
9. Make sure doors, lids, and access panels are closed.
10. Confirm how to exit diagnostic mode before entering it.

Do not continue if the appliance presents an immediate safety risk.

How to Find the Correct Model Number

The model number is usually printed on a rating plate or product label.

Washing machines and dryers

Check inside the door, around the door frame, behind the appliance, or near the detergent drawer.

Dishwashers

Look along the upper or side edge of the open door.

Refrigerators

Check inside the refrigerator compartment, behind a drawer, or on an interior wall.

Air conditioners

Look on the indoor unit, outdoor unit, rear panel, or side label.

Ovens and microwaves

Check around the door frame, inside the door, behind the appliance, or inside a lower drawer.

Boilers and furnaces

Look on the front cover, side casing, control compartment, or installation label.

The model number identifies the product family. The serial number normally identifies one individual appliance.

How Diagnostic Mode Usually Works

The exact steps vary, but a diagnostic procedure may involve:

1. Placing the appliance in standby mode.
2. Closing the door or lid.
3. Pressing selected buttons in a set order.
4. Holding one or more buttons for several seconds.
5. Turning a selector dial through a sequence.
6. Waiting for lights or display symbols to change.
7. Reading stored fault codes.
8. Selecting a test using buttons or a control dial.
9. Ending the test through an exit command.

Never assume that one sequence works across every model from the same brand.

A sequence used on one Whirlpool washer, for example, may not work on another Whirlpool series.

How to Read Stored Error Codes

When diagnostic mode displays a code:

• Write down every letter and number.
• Record the order in which codes appear.
• Note whether the code is active or stored.
• Check whether the display alternates between two code groups.
• Repeat the sequence only if the guide instructs you to.
• Take a photograph or short video of the display.

Some appliances show the newest code first. Others display faults in the order they occurred.

A stored code does not always mean the fault is still active. It may relate to an earlier event.

Active Codes and Stored Codes

Active error code

An active code relates to a condition the appliance is detecting now.

Stored error code

A stored code records a problem that happened previously.

Pending or intermittent fault

The appliance detected a problem temporarily, but it may not occur during every cycle.

Service reminder

Some messages are maintenance notifications rather than actual fault codes.

Compare the code with the appliance’s current symptoms before deciding what it means.

Safe Tests for Homeowners

Some manufacturer-approved diagnostic tests may be suitable for users when they involve only:

• Reading stored codes
• Checking button response
• Checking door or lid status
• Running an empty test cycle
• Confirming whether water enters or drains
• Checking visible fan or light operation
• Exiting a frozen control state

Stop if a test requires:

• Removing panels
• Touching live wiring
• Bypassing a safety switch
• Testing gas components
• Opening a sealed cooling system
• Measuring internal voltage
• Running exposed moving parts
• Changing technical calibration
• Entering protected service settings

Settings You Should Not Change

Some service menus contain values intended only for trained technicians.

Do not change:

• Gas pressure settings
• Combustion values
• Refrigerant settings
• Compressor protection values
• Motor calibration
• Temperature calibration
• Water-level calibration
• Safety limits
• Control-board configuration
• Model identification settings
• Factory programming
• Component test duration

Changing technical values may create unsafe operation, damage the appliance, or affect warranty coverage.

How to Exit Diagnostic Mode

The exit method depends on the appliance.

Common methods may include:

• Pressing Cancel or Power
• Holding a specific button
• Turning the selector to Off
• Completing the diagnostic cycle
• Selecting an exit command
• Disconnecting power after the appliance has stopped safely

Do not disconnect power while the appliance is filling, draining, heating, spinning, or completing a safety process unless an emergency requires immediate isolation.

After exiting:

1. Wait for the appliance to return to standby.
2. Check whether the code remains.
3. Run only a simple, safe test function.
4. Stop if the fault returns.
5. Record any new code that appears.

What If Diagnostic Mode Will Not Start?

Possible reasons include:

• Wrong button sequence
• Incorrect model instructions
• Control lock enabled
• Door or lid not closed
• Appliance not in standby
• Buttons not responding
• Selector dial in the wrong position
• Fault preventing service mode
• Different regional control panel
• Procedure intended for technicians only

Do not keep trying random button combinations. Search using the complete model number and region.

What If No Error Code Appears?

A fault may still exist even when diagnostic mode shows no stored code.

Possible causes include:

• Intermittent wiring problem
• Mechanical blockage
• Worn component
• Poor water or airflow
• Loose connection
• Fault outside the appliance
• Problem not monitored by the control system
• Error history recently cleared
• Incorrect diagnostic procedure

Use the appliance symptoms, model information, and official service guidance to continue the diagnosis.

Clearing Stored Error Codes

Some appliances allow stored fault codes to be cleared.

Do not clear codes before recording them. The error history may help identify an intermittent problem.

Only clear codes when:

• The exact procedure has been verified
• Every code has been recorded
• The original issue has been checked
• You understand that clearing does not repair the fault
• A manufacturer or qualified technician recommends it

After clearing, run a safe test and check whether the code returns.

Regional and Model Differences

Diagnostic procedures can differ between models sold in:

• United States
• Canada
• United Kingdom
• Ireland
• Australia
• New Zealand
• Europe
• Other regions

Differences may include:

• Button layout
• Voltage
• Product firmware
• Model numbering
• Error-code format
• Service menu access
• Component configuration

Always confirm the model and regional version.

When to Call a Technician

Professional diagnosis is recommended when:

• The same code returns after basic checks
• The appliance trips a circuit breaker
• Wiring looks burned or damaged
• A gas or burning smell is present
• Water is reaching electrical parts
• The appliance overheats
• A compressor or sealed system is involved
• Internal voltage testing is required
• A motor, control board, or heating circuit must be tested
• The service menu requires calibration
• The appliance is under warranty
• You cannot verify the correct diagnostic procedure

Provide the technician with:

• Brand
• Model number
• Serial number
• Country
• Stored codes
• Active codes
• Symptoms
• Photos of the display
• Tests already completed

Important Safety Information

Stop using the appliance if you notice:

• Smoke
• Sparks
• Burning smells
• Gas smells
• Water near electrical parts
• Severe overheating
• Damaged wiring
• Repeated circuit-breaker trips
• Refrigerant leakage
• Loud grinding or metal contact
• Unsafe door or lid operation

Do not bypass safety locks, switches, sensors, fuses, or protective controls.

Repairs involving electricity, gas, combustion, refrigerants, sealed systems, internal wiring, or major disassembly should be performed by qualified professionals.

Frequently Asked Questions

Is diagnostic mode the same as resetting the appliance?

No. A reset restarts the control system. Diagnostic mode displays fault information or runs tests.

Can diagnostic mode repair an appliance?

No. It can help identify a fault, but it does not repair blocked hoses, failed sensors, damaged wiring, worn motors, leaking systems, or defective components.

Is it safe for homeowners to use diagnostic mode?

Reading codes or running a manufacturer-approved empty test may be safe on some models. Technician-only settings and internal tests should not be used without proper training.

Can the wrong button sequence damage the appliance?

It may enter another mode, change settings, start a test, or create confusion. Use only instructions verified for the exact model.

Why are several error codes stored?

The appliance may have recorded different faults over time. One code may be the main problem, while others may have appeared as a result.

Should I clear error codes after reading them?

Record every code first. Clearing the history does not fix the cause and may remove useful information for a technician.

Why does diagnostic mode show no fault?

The problem may be intermittent, mechanical, external, or not monitored by the control system. The diagnostic procedure may also be incorrect for the model.

Can I use a diagnostic guide from a similar model?

Not unless the manufacturer confirms that both models use the same controls and procedure.

Is Error Code Vault affiliated with appliance manufacturers?

No. Error Code Vault is an independent informational website. Brand names, product names, model numbers, and trademarks belong to their respective owners.