LG Washer Diagnostic Mode: How to Enter and Read Results
Quick Answer
Enter LG Washer diagnostic mode to read stored fault codes and run individual component tests. See the entry sequence below. Diagnostic mode stores recent error events so you can find intermittent faults that clear between uses.
Look, diagnostic mode is the difference between guessing and knowing. I've watched homeowners drop $200 on parts that weren't even the problem because they skipped this step. If your LG is throwing codes or acting weird, spend 5 minutes in service mode first. You'll know exactly what's broken before you order anything. Skipping it usually just means a second repair trip.
LG ThinQ app (for Smart Diagnosis, iOS or Android), Phillips #2 screwdriver
LG Washer Diagnostic Mode: How to Enter and Read Results
OK so here's the deal with LG's diagnostic mode. It's basically a built-in test menu that's been in LG washers going back to the mid-2000s. You can fire up each component one at a time, pull stored fault codes, and catch stuff that only fails intermittently. Honestly, I run this on pretty much every single LG call I go out on. It saves a ton of time versus swapping parts and hoping for the best.
Most Likely Causes
Based on aggregated repair data, here is the probability breakdown for this error code:
Need to confirm which component is causing a specific error code before buying parts40%
Intermittent error that does not reproduce during normal cycles36%
Technician service visit requiring component-level verification24%
Symptoms You May Notice
An error code showed up once or twice but keeps clearing itself before you can figure out what caused it.
The drum spins but sounds wrong, or the machine fills really slowly, or it stops mid-cycle with no obvious reason.
You replaced a part based on a code and the exact same code came back within a few washes.
No error code at all, but clothes are coming out soaking wet because the spin isn't reaching full speed.
Cycle times seem way longer than normal and the machine isn't cleaning well, but nothing's showing on the display.
Can you reset a Lg washer to clear the DIAG code?
To clear stored fault codes after your repair, enter diagnostic mode using your model's button combo and cycle to the fault code display, then press and hold Start/Pause for 5 seconds. Display should clear. You can also unplug the washer for 5 full minutes, plug back in, and run a complete cycle. The fault log clears automatically once the underlying issue is fixed and the machine finishes a successful wash without re-triggering the same code.
Tools Required for Diagnosis
LG ThinQ app (for Smart Diagnosis, iOS or Android)Phillips #2 screwdriverMultimeter set to resistance (ohms) modePhone or tablet with camera to photograph test sequences and error codesPen and paper to log fault codes during diagnostic mode
Diagnostic Checklist
Follow these steps in order. We start with the easiest external fixes before opening up the machine.
Did the fix not work?
If the problem comes back after following these steps, a component has permanently failed and needs replacement. Check the specific error code your washer is showing:
Front-loaders (WM series): hold Start/Pause and Temp at the same time, then press Power while you're still holding both. Let go when the display changes to tSt or a test number. Top-loaders (WT series): hold Temp and Rinse for 3 solid seconds. WT7300 and WT7800 use Wash Temp plus Spin Speed instead. Timing matters here, hold for a full 3 seconds and don't let go early. If the combo isn't working, check the inside of the door frame. Some models have the service entry sequence printed on a sticker right in there, which saves a lot of head-scratching.
What is the button sequence for LG washer diagnostic mode?
Most common for WM front-loaders: hold Start/Pause and Temp simultaneously, then press Power. For WT top-loaders: hold Wash Temp and Spin Speed for 3 seconds. Older WM models from around 2006 to 2012, like the WM1333, WM2455, and WM2650, often use the last two cycle option buttons while pressing Power instead. If none of those work, your model might need a slightly different combo. The LG service manual for your exact model number will have the right sequence and those PDFs are pretty easy to find if you search your model number plus 'service manual.'
Can I run diagnostic mode without the ThinQ app?
Totally. The button-sequence service mode works on every LG washer, Wi-Fi or not, going back years. ThinQ Smart Diagnosis is faster and gives you plain-English results, but it's reading the same underlying data. The built-in service mode actually gives you more control because you can fire individual components one at a time and watch what happens. I prefer the manual service mode for anything where I need to physically verify whether a part responds. Smart Diagnosis is great for a quick check. If you're doing a real hands-on diagnosis, the button combo method is where you want to be.
Is diagnostic mode safe to use?
Yeah, with some basic common sense. Keep the panels on if you can, and if a test requires you to watch something inside the machine, keep your hands clear while the test is running. The valve tests will actually let water into the drum, so make sure your drain hose is properly seated in the standpipe first. Don't run heater tests with an empty drum, that's the one that can actually cause damage if the element fires dry. Motor tests spin the drum, so no reaching in during those. Beyond that it's pretty low risk, especially compared to just guessing and replacing parts blind.
What do the test numbers mean in LG diagnostic mode?
Each number activates a specific component. On WM front-loaders the general pattern is: 1 = hot water valve, 2 = cold water valve, 3 = recirculation or bleach valve, 4 = drain pump, 5 = door lock, 6 = motor forward and reverse, 7 and 8 = heater element, 9 = drum light or display test. WT top-loaders follow a similar logic but the numbering shifts a little. When you press Start on a test number, that component gets power. If it doesn't respond, that's basically your answer. If it does respond, you can rule it out and move on. I ran this sequence three times last week alone and it nailed the problem each time.
How do I read stored error codes in LG diagnostic mode?
Once you're in service mode, the stored fault history is usually in the first couple of test screens. Look for 'Er' followed by a code on the display. On some models you scroll to a specific test number, often test 0 or somewhere in the 14 to 16 range, to see the full fault log. Write down every code you see, even old ones, because sometimes what looks like one problem is actually a chain of related faults. After you fix the root cause and run a complete successful cycle, those stored codes should clear on their own. If they don't, you can manually clear them by holding Start/Pause for 5 seconds while you're on the fault display screen.