A musty smell in the LG WM4500HBA has these causes in LG's manual: too much or the wrong detergent, a drum that was not cleaned properly, a door gasket and seal that are not cleaned regularly, foreign substances left in the drain pump filter, and a drain hose that siphons because it is installed wrongly. The cure is to run the Tub Clean cycle regularly, wipe the door and seal after each wash, leave the door open to dry the drum and clean the pump filter.
Differential
Likely causes of “LG front-load or top-load washer smells musty, sour or like mildew”, and how to tell them apart
- 1
A drum that has not been cleaned with the Tub Clean cycle
What separates it A musty smell from the drum and the tcL alarm has been showing
How to confirm Check how long since the last Tub Clean; the tcL message means it is time to run it
- 2
A door gasket and seal that are not cleaned
What separates it Black or slimy spots under the folds of the door seal
How to confirm Open the door and look under the seal; LG says mold or foreign substances there cause odor
- 3
Foreign substances in the drain pump filter
What separates it The smell is strongest at the pump filter and the filter is dirty
How to confirm Open the pump filter cover and look at the filter for debris
- 4
A drain hose that siphons
What separates it A sewer-like smell and water flowing back into the washer
How to confirm Check that the drain hose is not kinked and its end is not lower than allowed
Before you touch a setting
Record this first — changing settings destroys the evidence
- When Tub Clean was last run and whether the tcL message has been showing
- Where the smell is strongest: drum, door seal, drain filter or the drain hose
- Whether the door is left open after a wash and how much detergent you use
Try in this order
0 of 5 completedRun the Tub Clean cycle
ReversibleThe tc L message means it is time to run the Tub Clean cycle, which LG says is not an error code. Run it regularly to clean the inside of the drum.
Wipe the door and seal after each wash
ReversibleLG says to wipe the door and the inside of the door seal to remove moisture, wipe the body dry and leave the door open so the drum interior dries.
Check under the seal
ReversibleLook under the door seal for small items when you unload; foreign substances left there cause odors.
Clean the drain pump filter
ReversibleUnplug the washer, drain the remaining water into a bucket and clean the pump filter and its opening, since foreign substances in it cause odors.
Fix the drain hose and the detergent
ReversibleMake sure the drain hose is not kinked or blocked so it cannot siphon, and use only HE detergent in the recommended amount.
Model-specific
What is true of this model and not of its siblings
- Odor prevention from the manual
- Run Tub Clean regularly, wipe the door and seal, leave the door open, clean the pump filter regularly and use only HE detergent.
- Tools and supplies
- Towels, a soft cloth, a bucket for the pump filter and a flashlight.
- Parts for this problem on the WM4500HBA (RepairClinic, 2026-09-20)
- clamp, part number ACA56078801, at $22.94; pump assembly,drain, part number AHA75853813, at $69.18.
- Other models this page answers
- These steps also fit models WM6500HBA, WM5500HWA, WM4200HWA, WM4000HWA, WM3600HWA, WM3400CW, WM8900HBA, WM9500HKA, WM6998HBA, WKEX200HBA, WKEX300HBA, WT7900HBA, WT7400CW, WT7300CW, WT7150CW, WT6105CW, WD300CV.
Stop boundary
When this stops being a self-service repair
- !If the smell is of burning or hot plastic, stop the washer and unplug the washer at once
- !If the odor persists after Tub Clean, a clean seal and a clean pump filter, call LG service
Evidence ledger
Sources behind this answer
LG USA support page listing this model's manuals and warranty.
Parts and list prices as shown on RepairClinic's parts search for this model number on 2026-09-20.
Exact questions
Common questions
Why does my LG WM4500HBA smell musty?+
Too much or the wrong detergent, an unclean drum, an unclean door gasket and seal, foreign substances in the pump filter, or a siphoning drain hose.
What does tcL mean?+
The Tub Clean alarm: it is time to run the Tub Clean cycle. It is not an error code.
Is a new-washer smell normal?+
Some odor comes from the rubber attached to the washer; LG says it is normal for new rubber and disappears after the washer has been run a few times.
Should the door stay open?+
Yes. Leave the door open after a wash so the drum interior dries.
Do damp clothes cause odors?+
Leaving damp items in the washer can cause wrinkling, color transfer and odor; remove items as soon as the cycle is complete.
Can the drain hose cause a smell?+
Yes. If the drain hose is not installed properly, siphoning can occur, and odors can follow.
Does more detergent help?+
No. Using too much detergent will cause poor wash and rinse performance and may contribute to odors.
Is the dryer-model odor advice for me?+
The dry-function odor advice in the manual applies to combination models only; this washer has no dry function.