Diagnostic mode can show stored fault codes or test selected appliance functions, but the procedure is not the same for every model. Find the exact model number and check the manufacturer’s instructions before entering any test or service menu.
Start here: If the appliance shows an error code, record it first. Do not try a button sequence from a different model or enter technician-only settings. Stop using the appliance if you notice smoke, sparking, a gas smell, severe overheating, or water close to electrical components.
Find a Diagnostic Mode Guide
Search using your appliance brand, full model number, and the words diagnostic mode, test mode, or service mode. The search checks the guides published on Error Code Vault.
Useful searches: LG washer diagnostic mode, Bosch dishwasher test mode, GE refrigerator diagnostics.
Browse by Appliance
Washing Machines
Fault history, controls, filling, draining and spin tests on supported models.
Refrigerators
Control displays, cooling faults and supported self-test functions.
Air Conditioners
Fault displays and operating information where consumer access is supported.
These links open WordPress searches; they are not claims that a dedicated diagnostic guide exists for every appliance or brand.
What Diagnostic Mode Can Tell You
Depending on the model, a diagnostic or self-test function may display current or stored faults, check a control panel, or run an automatic test. Some service modes also activate pumps, fans, motors, heaters or valves. Those functions are not necessarily appropriate for homeowners.
| Function | What it may show |
|---|---|
| Fault history | Previously recorded error codes, not necessarily active faults |
| Display or button test | Whether selected interface controls respond |
| Automatic test cycle | Responses from certain systems during a short sequence |
| Service settings | Technical values that may be restricted to qualified personnel |
A diagnostic code can point toward a circuit or operating condition without proving that one particular component has failed. A passing short test also does not rule out an intermittent problem during normal use.
Before You Run a Test
- Record the symptom and exact code. Photograph the display before resetting or clearing any fault history.
- Find the full model number. Check an accessible product label or your purchase documentation. Do not remove service panels to find it.
- Open the correct manufacturer manual. Confirm that its instructions cover your model and country or region.
- Confirm whether the procedure is user-accessible. Do not enter menus identified for technicians or service engineers.
- Understand the test and how to stop it. Some supported routines move the drum, fill, drain or heat. Follow the manufacturer’s preparation and exit instructions exactly.
Need help finding the right document? Read How to Search for a Model-Specific Appliance Manual.
Diagnostic Mode vs Reset
A reset attempts to restart or clear a temporary control state. Diagnostic mode investigates faults or runs tests on supported equipment. Neither process repairs a damaged part or resolves an unsafe condition by itself. If the same fault returns, repeated resets are not a substitute for diagnosing its cause.
Read Reset vs Diagnostic Mode: Which Should You Use First? for a clearer comparison.
If the Test Will Not Start or Shows No Code
First recheck the model-specific instructions, the appliance’s standby state and any manufacturer-listed conditions such as a closed door or unlocked control panel. Do not keep trying random button combinations. A different control-panel revision may use another process, or the service function may not be available to consumers.
No stored fault code does not prove the appliance is healthy. Mechanical restrictions, intermittent faults and problems outside monitored circuits may not appear in the short test. Record what happens during normal operation and use the relevant troubleshooting guide.
When to Stop and Call a Professional
Do not perform live electrical measurements, gas or combustion adjustments, refrigerant work, microwave internal tests, safety-switch bypasses, or tests requiring exposed moving parts. Stop if a routine behaves unexpectedly, changes settings you do not understand, or the appliance develops a safety warning.
Qualified service is appropriate when the manufacturer restricts a procedure to technicians, the fault returns after safe checks, or the next step requires internal inspection. Record the complete model number, displayed codes and observed symptoms to help the technician.
Find the Next Guide
If diagnostic instructions are unavailable for your model, begin with symptom-based checks or contact us to suggest a missing guide.